SpreeGridFeed
I would NOT use this yet while I am tweaking. Adds /products.xml and /t/taxon.xml feeds. Warning, it was designed for Alarm Grid, so I make no guarantees it will work for your store.
Example
Pretty easy, just add it to your gemfile:
gem 'spree_grid_feed', :git => 'git://github.com/ehoch/spree_grid_feed.git'
Bundle install and done.
Testing
Be sure to bundle your dependencies and then create a dummy test app for the specs to run against.
$ bundle
$ bundle exec rake test_app
$ bundle exec rspec spec
Copyright (c) 2012 Eric Hochberger, released under the New BSD License