What is your shortlist for hot/popular/trendy Open Source Projects?
mbrubeck: WebKit/Chrome/V8 are leading the way in web standards implementation, with Firefox/Gecko/TraceMonkey also doing lots of great stuff.Haskell is really taking off, both in terms of compiler improvements and in the size of the community and available libraries.  I'm using it for several projects now.MagLev, LuaJIT, Unladen Swallow, and V8 (again) are all exciting because they're bringing modern dynamic language VMs closer to Java-like (and sometimes even C-like) speeds.Android - my phone runs an open source OS, I can install software on it without an app store, and it can run SSH, Python, and Lua.  Sweet!