Try some problems at
http://rubeque.com/ or
http://www.codeeval.com/. Project Euler is also good, as duggieawesome suggested. As you're doing the problems, try and find "Ruby-esque" ways to solve them.
Other than that, run through the http://RubyMonk.com lessons, and try some of the Ruby courses at http://CodeSchool.com.
The best way to learn is with hands-on stuff though. So, if you're looking to get into Rails as well, I'd recommend what jfaucett recommended: try and pick a (simple) app to build, and build it.
I'm not sure what town your in, but if you don't see any meetup groups (check http://meetup.com .. or search Google), then why not create one?
I've heard that meetup.com can increase attendance to these meetups significantly, but I think it depends on which town your in. (I.e. if people in your town don't know about meetup.com, then it doesn't matter and you can get away with a website and marketing it another way [try reaching out to Python/Perl/Web Design groups and see if anyone would be interested in meeting up to talk or learn Ruby]).
If you'll be meeting with a bunch of people who are new to Ruby, going through RubyMonk.com together can be a good way to get people up to speed. Then try Rails for Zombies Redux at http://www.codeschool.com/courses/rails-for-zombies-redux (it's free).
But, yeah, practice, practice, practice. If you want some intermediate level stuff to work on, try creating a Rails app. You'll likely come across some intermediate-level stuff.
And good on ya for looking to improve your skills and get active in a local community. That's great! :)
I hope this helps.
