The forge version works great however I have had to remove dimensional doors from the server as it causes issues with showing player positions.
for example after quitting minecraft the dynmap showed I was still online even after 8 hours
think you are looking for dynmap
you will need alot of ram on the server to run it.
it can use up to 3gb of ram to run (this is a lot more than what it uses when installed on a bukkit server)