You can download a project template called a Web Deployment Project (WDP) (VS2008 version here), which enhances the build and deployment features of Visual Studio. This basically wraps features of aspnet_compile.exe, but allows you to do this visually as part of your overall solution.
Besides pre-compilation, it also allows you do a number of interesting things, like config file replacement (great for deploying to different environments) and setting how your assemblies are built (per-page, per-site, etc.).
Two good Scott Guthrie blogs about this project type:
I've used this project type for some VS2005 and VS2008 projects and it's invaluable (especially for those legacy web site projects!!).
I didn't know this was also in the MSDN library, but here's a nice article in MSDN for WDP's.
I hope this helps!
EDIT:
WDP's exist for VS2005 and VS2010 also.