I was introduced to ctags back in the 90's when I worked on my first really large system (the trading system at the Philadelphia Stock exchange) and became an instant fan.
Since I'm somewhat of a packrat, over the years I've stashed away nearly all of the code I've written - migrating source from paper tape -> cards -> 8"FD -> 5-1/4"FD -> 3-1/2"FD -> CD -> DVD -> FLASH and now have about half of it on my iMac to minimize the amount of time spent re-inventing old wheels. My TAGS file is about 44MB and the ctags capability makes instant access to everything possible. All I have to do is remember the name of the module, the name of a module that called the one I'm interested in, or (worst case) the name of any module in a system that incorporated the module.
I'm also using exuberant ctags, and it's working well for me.