I have a web project (the original 2005 web project type, not a web application project) and had a problem getting files copied to the bin directory. Essentially, one of the library projects referenced by the web project has an XML file in the project output, but when the solution is built, the XML file in the bin directory of the library project is not pulled into to the bin directory of the web project. Of course, a post-build event seemed like the thing to do, but web projects don't have support for that.
A little digging and I found this post by Scott Guthrie that describes a "Build Helper Project". You simply add an empty class library project to your solution. You then use the build events in the empty project use to add build events to your web project. You just make sure the project build order is correct so the events get called when you need them.