What are the available (best) ruby IP-based geolocation gem/plugins?
How do they compare to one another in terms of functionality, performance and ease of use (e.g. do they interact with a web service, or require a separate database, etc.) ?
I'm hoping anyone that has used some can share their experience and give recommendations.
Your current best bet is probably GeoKit (http://github.com/andre/geokit-gem for gem, http://github.com/andre/geokit-rails for plugin). It has built in functionality for Yahoo and Google API keys, distance calculation helpers, reverse geolocation, etc.
However, GeoMereLaal (http://github.com/parolkar/geo%5Fmere%5Flaal/) is based on the working draft of the W3C Geolocaton API. It's very limited at the moment as I could only get it to work in Firefox, but it will be more accurate as it's supported by more browsers since it uses more methods of Geolocation (GPS, WiFi, cookies, IP).
Easier to use and faster to set up, but with less features: http://humbuckercode.co.uk/licks/gems/geoip.
No external queries, no schema changes and quite fast.