True, thought it is important to be realistic about your ability in terms of time/skills to do so. For OSS I like for one of three things. Either "too big to f

True, thought it is important to be realistic about your ability in terms of time/skills to do so. For OSS I like for one of three things. Either "too big to fail" (i.e Linux , Rails). Interchangeability , i.e something built on top of an open protocol like an SMTP server. Or something with < ~10KLOC in language I am familiar enough with that I would feel comfortable folding the entire thing into the codebase as a whitebox.