Resque
Ruby library for creating background jobs and processing them
...Your existing classes can easily be converted to background jobs or you can create new classes specifically to do work. Or, you can do both. Resque is heavily inspired by DelayedJob (which rocks) and comprises three parts, a Ruby library for creating, querying, and processing jobs, a Rake task for starting a worker which processes jobs, a Sinatra app for monitoring queues, jobs, and workers. Resque workers can be distributed between multiple machines, support priorities, are resilient to memory bloat / "leaks," are optimized for REE (but work on MRI and JRuby), tell you what they're doing, and expect failure.