Join the mailing list
You can join the mongrel2@librelist.com mailing list.
The mailing list is the best way to get help if you can wait or if you have more detailed needs. It's low traffic and easy to get off if you want.
Chat on IRC
We hang out in IRC on irc.freenode.org in the #mongrel2 channel.
Join the IRC channel if you want to ask a question real quick, but if nobody is there then try back later.