You can run site-to-site vpn as well as easy vpn server on the same router, however, you won't be able to run site-to-site vpn and easy vpn client on the same router.
For site-to-site vpn as well as easy vpn server, you just have to create 1 crypto map with multiple sequence (site-to-site vpn will have the static crypto map entry and should have higher sequence (10 for example) then the easy vpn server (dynamic crypto with lower sequence) - 65000 for example. Easy vpn server is similar to creating vpn client to connect to the router.
Hope that makes sense.
