You will get the following games:
Tier 1: $1US
Frozen Synapse (also DRM free) http://store.steampowered.com/app/98200/ ($24.99US)
Frozen Cortex http://store.steampowered.com/app/237350/ ($24.99US)
Lux Delux http://store.steampowered.com/app/341950/ ($9.99US)
Shattered Planet (also DRM free) http://store.steampowered.com/app/305640/ ($14.99US
Tier 2: BTA currently at $4.53US
The last federation (also DRM free) http://store.steampowered.com/app/273070/ ($19.99US)
Reassembly (also DRM free) http://store.steampowered.com/app/329130/ ($14.99US)
Tier 3: $15US
Chaos Reborn http://store.steampowered.com/app/319050/ ($19.99US)
Big Pharma (also DRM free) http://store.steampowered.com/app/344850/ ($24.99US)
NOTE: You will get TWO Steam keys for Frozen Cortex when you buy. You will get the second key after you activate the first on Steam.
EDIT: Apparently Humble Bundle made a mistake and you only get ONE copy of Frozen Cortex despite their page saying you get TWO - maybe they fix it later, maybe they do not. Just do not rely on that second copy.
Enjoy
You only get 1 Frozen Cortex. The description on HB is incorrect.