I\'ve never used CI tools before, but from what I\'ve read, I\'m not sure it would provide any benefit to a solo developer that isn\'t writing code every day.
First
If you need to support multiple compilers then it's handy to have a CI build system to do all of that whilst you just develop in one IDE. My code builds with Vc6 through VS2008 in x86 and x64 builds on VS2005 & 8, so that's 7 builds per project per project configuration... Having a CI system means that I can develop in one IDE and let the CI system prove that all of the compilers that I support still build.
Likewise, if you are building libs that are used by multiple projects then CI will make sure they work with ALL of the projects rather than just the one that you're working with right now...