After
this thread, I thought it'd be interesting to know what plug-ins people prefer.
Mine are:
Forecast Fox - an extension that brings international weather from The Weather Chanel® to your Firefox web browser.
BetterSearch - which enhances Google (all international flavours, too), MSN Search, Yahoo Search, A9, AllTheWeb, del.icio.us and Simpy.com by adding previews (thumbnails) and Amazon product images and info (type, price, rating for US/DE/UK/CA/FR products), a quick preview as well as "Open in New Window", "Site Info" and "Wayback Machine" links to the search results.
FlagFox - which displays the flag of the location of the current server. It achieves this by using an IP address to country database rather than domain-name top-level-domains (eg ".uk" or ".br"), and so works with all sites - useful to ensure you're not being spoofed about a server's location.