If by chance you have an iPhone, there's an app called "Electronics Toolbox" that has a great transistor database, among other handy things. Lists most pertinent info for any transistor you can think of, plus lists some compatible replacements.
hmm, great tool, however I note that the first transistor I look up (2N3055) is listed with a Ptot of 5W, fortunately the "compatible types" were what you expect