Depends on whether you'd like to pay or not - and whether the critique groups I mention will "fit" with your story (and you, naturally

).
If you think your novel leans toward spec fic (SF, fantasy), then you can try:
http://sff.onlinewritingworkshop.com
This is a paying online crit group, although if I remember correctly, you can "try them out" for about a month. If you want to join after that point, I believe it's US$49 for a year.
A free crit group for spec fic:
http://www.critters.org
Now, if what you want is just a general purpose crit group, since you're not sure if your novel fits into the spec fic world, here are a couple:
http://www.critiquecircle.com
http://fmwriters.com/index.html
Both Critique Circle and Forward Motion Writers' Community (started up by Holly Lisle) are free.
And there's also one talked about on this board, I think under writing mentors or some such:
http://www.fictionline.net/TWC/phpBB2
It's free, but the owner of that board says he wants to limit it to about 30 people; sounds like he's trying to keep it as intimate as an online crit group can possibly be. He also probably wants to have an easier time policing the board.
As of this morning, there were 22 people part of that group.
I don't really have time to join a local crit group (and I know there is one); I get up at 4:30 in the morning, don't come home until 6:00 (lots of traffic both ways). By the time I get home, even walking the dogs requires considerable effort. I can do it, but it's not easy!
Welcome, and good luck!
~Nancy