I've been using Exuberant Ctags, version 1.5, by Darren Hiebert for the past little bit now and really like this a lot. As the name implies, it does a pretty thorough job of scouring your source files for all sorts of useful stuff -- function declarations, typedefs, enum's, variable declarations, macro definitions, enum/struct/union tags, external function prototypes, and so forth. It continues on in the time honored tradition of providing a bazillion options, but not to fear: it's default behavior is sane and savvy and provides a very nice OOBE*.
*(Out Of Box Experience)
...This one is definitely worth having.