ResGen
ResGen is a program that can automatically create res files based on your bsp. Most of the time it works correctly, however, it is not perfect.
If you need to do a quick res file and don't have the time to create your own, using the regen creator would be preferable to not doing a res file at all.
ResGen does NOT include mdl files with letters or numbers begining with "0" at the end; zombie.mdl=yes, zombieT.mdl=no, zombie01.mdl=no. These lines will have to be added manually to the respective models line of the res file.