A few beers and some music usually help me to get an idea for a project.
Just don't have too many before starting a project, you wouldn't want to get up the next morning and realize your project was written in python ;-)
To answer your question, I find that after I complete a boring task for the 15th time, I usually have a fair bit of inspiration to automate the procedure. So I guess you could say laziness is my inspiration :)
Other than that, I find that looking around CPAN and trying out new modules helps me get ideas for neat projects. Reading questions around here and seeing common problems also makes for a lot of interesting projects as well.