9 Great Ruby Libraries from Robot Co-op
cached_model: A subclass of Rails' ActiveRecord::Base that caches objects in memory using memcached. Big speed improvements in many circumstances.
geocoder-us: A library that accesses geocoder.us's geocoding API that lets you look up addresses and turn them into coordinates.
google-geocode: A library that uses the Google geocoding API to the same effect as the previous library.
memcache-client: A pure Ruby client for memcached, the great memory cache system.
yahoo-search: Bindings to Yahoo's search API.