Host own webpage / server for testing purposes?

Myself and a colleague of mine are trying to figure out how to use our computers to host web pages for testing purposes. For example, it’d be nice if we could edit HTML and PHP / XML files locally, and just cut out the step of uploading to a hosted page. So… how would we go about doing that? Seems like with the remote IP it could be easy enough.

Ideas?

edit: We’re both behind routers, if it matters.