upr is Rack middleware that allows browser-side upload progress monitoring. It is based on (and should be client-side compatible with) several upload progress modules including ones used by leading web servers. It allows any Moneta backing store in addition to DRb. There is also a packaged example for using an ActiveRecord model for Rails.
Gemfile gem 'upr', '~> 0.2.0'
install gem install upr -v 0.2.0