While the Serious Sam franchise is repeatedly discounted, I'm not sure I've come across a better deal than this Humble Weekly Sale. It's pay-what-you-want pricing for Serious Sam HD: The First Encounter, Serious Sam HD: The Second Encounter, Serious Sam: The Random Encounter, Serious Sam Double D, Serious Sam: Kamikaze Attack!, and Serious Sam Public Test 2.
Putting in more than $1 will award you Steam keys, while beating the average unlocks Serious Sam II and Serious Sam 3: BFE. Does anyone need this much Sam in their life? Well, yes -- of course! There's also the fact that this will "help contribute to the production of Croteam's next project" which is none other than Serious Sam 4. What, no subtitle?