Couldn't see this posted yet; the Deus Ex collection, part of the Square Enix sale on Steam at the moment.
Includes the following (with individual prices also reduced):
Deus Ex; GOTY Edition $2.49 USD
Deus Ex: Invisible War $2.49 USD
Deus Ex: Human Revolution $6.24 USD
Deus Ex: Human Revolution - Explosive Missions Pack $0.74 USD
Deus Ex: Human Revolution - Tactical Enhancement Pack $0.49 USD
Deus Ex: Human Revolution - The Missing Link $3.74 USD
There's also the Deus Ex: Human Revolution Augmented Edition which is bundled with the Explosive Missions and Tactical Enhancement Packs for $8.74 USD.
Also, first post so apologies if I'm missing any details.
Wicked price.. the original also has a HD Texture pack available by a group of modders (New Vision - http://www.moddb.com/mods/new-vision )
Edit: Also might be worthwhile mentioning you can buy the standalone Human Revolution for $6.24 http://store.steampowered.com/app/28050/?snr=1_6_4__421