Recs.
Updated
Specs
Pros
Pro Also carries GOG, UPlay and/or Origin keys as well as Occulus Rift etc.
Humble Bundle sometimes provides choice between an alternative key (for example: GOG DRM-Free or Rockstar Games and a Steam key (not both)). Convenient for those don't have or don't want DRM-unfriendly Steam accounts. Clear key redemption instructions are provided in such cases.
Pro No VAT for Europeans
Unlike some sites where you get charged an additional 20% upon checkout, HB does not include the VAT "on top" of what the bundles cost. So, no surprises or need to use a proxy.
Pro Pay what you want
The way Humble Bundle works is that it is donation based in that you can pay what you want for the bundle, with the minimum being a dollar. There are separate packages in each bundle that also ask for a minimum price, which depends on the "beat the average" price which is what on average has been donated so far..