Running Deals
https://www.humblebundle.com/
Humble Origin Bundle -
$1/Pay what you want - Dead Space, Burnout Paradise Ultimate Box, Crysis 2 Maximum Edition, Mirror's Edge, Dead Space 3, Medal of Honor
Better than Average (currently $4.76): Battlefield 3, The Sims 3 + Starter Pack
This one is a no brainer, even if you hate EA, all the profits are going to charity. Dead Space 3, Battlefield 3, and The Sims 3 can only be activated on Origin, the rest come with Steam and Origin Keys.
Also if you've never bought a bundle from Humble Bundle before, they usually add more games that get unlocked to previous purchasers in the second week, usually the net knows which ones due to how they do their bundles, but this one being all individual keys it's going to be a surprise (my guess Dead Space 2 will be one of them).
edit: Update looks like these will be the unlocked games next week added to the bundle
Humble Weekly Sale:
The PewDiePie sale (ick yes I know) 1$/Pay what you want - Botanicula, McPixel, Thomas Was Alone, The Showdown Effect
Better than average (currently $2.15) Amnesia: The Dark Descent
Worth it for Botanicula and Amnesia alone if you don't already have it. Botanicula is a great point and click adventure with killer art direction and sound design (have footage of it on my youtube), McPixel is a great humorous timewaster, Thomas Was Alone a minimal artsy platformer focused on narrative (haven't played it), The Showdown Effect I have no idea about, and Amnesia is a great horror game with plenty of mods for it.
The Indie Gala Summertide: 3 days remaining
http://www.indiegala.com/
Pay what you want: Miner Warfare, Doom & Destiny, Oniken
Tier 2 (currently $4.62): Space Pirates and Zombies, Exceed - Gun Bullet Children, Exceed 2nd - Vampire Rex, Aura: Fate of The Ages, Painkiller Redemtion
Tier 3 (currently $6.99): Exceed 3rd JPB Package, Sacraboar, Trainz Simulator 12, TS 12 - Aerotrain & Coronation Scot DLCs, Painkiller: Recurring Evil, Hydrophobia: Prophecy
I'm a fan of Oniken (throwback to old hard 2d platformers like Shatterhand) SPAZ is fun, the Painkiller sequels are hit or miss but great for fans of old school twitch shooters, Hydrophobia is pretty good as well.
Groupees Build a Doujin Bundle -
http://groupees.com/doujin
Minimum buy 2 titles $1.50 ($0.75 each) Cherry Tree High Comedy Club, Ether Vapor Remaster, War of the Human Tanks, Yousei, Yatagarasu, Croixleur, Cafe 0 The Drowned Mermaid, plus a bunch of unlocked bonuses you don't have to pay for
Only played a couple and these are def a niche fanbase type deal more for weeaboos. Cherry Tree plays kind of like Persona minus the combat, Ether Vapor is a fun shooter not riddled by bullet hell bullshit, War of the Human Tanks is a strategy game using a visual novel engine. The rest no clue, see what looks cool Yatagarasu is a 2d fighter from ex SNK on indiegogo so that could turn out awesome for fighting game fans.
Steam
http://store.steampowered.com/:
Kalypso 75% off weekend
Loads of titles in this deal ones worth checking out
Tropico series various prices for games in series and DLC - be El Presidente and run your island as a dictatorship how you see fit. Think Sim City, but Cuba style.
Patrician 3 $1.69/4 $6.79 - Historical trading sim
Port Royale 3 $9.99- Carribean in the 17th century, you're a captain who can become a trader, or privateer, kind of like Patrician with a twist
Sine Mora $3.39- gorgeous sidescrolling shooter which isn't an insanely difficult bullet hell
Anna $3.39- really nice point and click adventure game with a great atmosphere.
AVOID Jagged Alliance Back in Action if you're a fan of the originals
The rest well Kalypso has a reputation of making mediocre games.
Red Faction Series 80% off - not going list them all here, but most are worth a play.
Midweek deals end today:
Monaco 75% off $7.49 - really fun co-op indie heist game
Sins of a Solar Empire 75% off $9.99 - don't know much about it, but damn it I will highlight space games as not enough get made anymore
Daily Deal:
Two Worlds 2 %80 off - Way better than the original which was a mess. Open world sandbox RPG. More suited to fans of the Gothic and Risen series than The Elder Scrolls, but they may enjoy it as well.
Other Specials:
Little Less than 24 hrs on this one: Thief Bundle %75 $4.74 - the grand daddy of Stealth games, buy this now if you call yourself a PC gamer and don't own them already.
Earthworm Jim Bundle %66 $6.79 - Earthworm Jim 1, 2 and 3D. If you don't know Earthworm Jim you had a horrible childhood and I feel bad for you.
MDK Combo %66 $5.09 - MDK 1 and 2 (not to be confused with 2 HD). Classic Action games from the same devs as Earthworm Jim, worth playing even now.
MDK 2 HD %66 $5.09 - modern HD remake of a classic.
GamersGate -
http://gamersgate.com/
Arma 2 Complete Collection %50 $19.98 - Arma 2, Operation Arrowhead and all the DLC. I love ArmA so biased, but if you were interested in DayZ all you need is Combined Operations. Not everyone's thing, but military sim/sandbox with tons of mods and very active MP community.
Arma X edition %50 $24.98 - Same as above, just includes ArmA 1 and it's expansions which while dated, you can use the maps from it in ArmA 2 and 3
XCOM Enemy Unknown %75 $9.99 - Modern take on the classic, had a blast with this one
Batman Arkham Collection %66 $15.28 - Both Batman games which are great, the individual games are on sale as well
X-Com Complete Pack %75 $3.74 - All the classic X-Com games. Some hit or miss, but the original and Terror From the Deep are worth it alone. Buy this now if you never played them.
Greenman Gaming -
http://www.greenmangaming.com/
Rockstar Games up to %80 off
GTA Complete Pack %75 $12.49
LA Noire Complete%80 $5.99
Max Payne 3 %75 $9.99
Max Payne 3 Rockstar Pass 80% $5.99
Bully/Manhunt pack %75 $6.24
Midnight Club 2 %75 $2.49
GOG -
http://www.gog.com/
Wargame: European Escalation %50 $9.99 - for those who wnt a really quality RTS experience set in the Cold War with tons of units and great multiplayer. Really a great game that gets overlooked.
Etherlords 50% $2.99
Etherlords 2 50% $2.99
S2: Silent Storm Gold Edition %0% $4.99 - Killer Turn Based Tactics game
D&D Classic Gems
It's odd how they do this, but the more you buy the more you save and it includes titles you already own so you already get that discount tier

Includes: Neverwinter Nights 2 Complete, Neverwinter Nights Diamond, Baldur's Gate Original Saga, Baldur's Gate 2 Complete, Planescape Torment, Icewind Dale Complete, Icewind Dale 2 Complete, Forgotten Realms Demon Stone, Dungeons & Dragons Dragonshard, The Temple of Elemental Evil
The whole shebang is $26.40 for all 10.
Most of these are must plays for CRPG fans, ToEE being one of my personal faves that gets overlooked.
Amazon -
http://www.amazon.com/Game-Downloads/
Street Fighter X Tekken 76% $11.99 - If you're a fan, just know the netcode is rather shit and tons of DLC
Super Street Fighter IV AE 76% $7.19 - For fans of fighting games, hope you have an arcade stick netcode is actually good, but downside uses GFWL which they'll be ditching in the upcoming Hyper edition.
Dark Void Zero 50% $2.49 - fun 2d throwback game, Capcom is good at these
Dark Void 50% $2.49 - 3d person action, looked kind of cool, but never played it can't really go wrong for the price though to check it out.
Psychonauts 75% $2.49
Stacking 75% $3.74
Costume Quest 75% $3.74
Brutal Legend %50 $9.99
Little Inferno %50 $4.99
Desura
http://www.desura.com/ -
99 Levels to Hell 70% - $1.79 A 2D-shooter/Dungeon-Crawler with rogue-like elements. Tons of replay value.
Millenium - A New Hope 60% $3.99 - Really well done point and click adventure.
For you UK heads
Gamefly - gamefly.co.uk
The Darkness 2 80% plus apply coupon code GFDAUG20UK £3.19