There are a lot of free icons (both vector and bitmap) floating around, but not many as nice as these. These icons would be perfect as bigger headlining graphics (here’s an example, but with uglier icons).

If minimalism is your thing, you have the always reliable Silk icons, which are popping up everywhere these days. By the way, there’s now a sprite version for Blueprint. A “sprite” is when you stick multiple images into one file and then display only parts of it at a time using the css background position property. Although it’s not very convenient in this case because you will rarely use all of Silk’s 700 icons on one page, in principle it can help decrease the number of http requests and improve loading times.

The more I think about it, the more I think widespread icon use is one of the not-so-obvious benefits of the “web 2.0″ design craze.