I stumbled across yet another online dictionary service the other day, but this one offers a little bit more than the standard single word definition service. MyDictionary.net offers dictionaries in twelve different languages, as well as translating words and phrases between these. It also has a foreign language keyboard display, which is handy, though quite tiny.
My favourite feature has to be the recent search display. The main page displays the last 20 or 50 searches completed, and I find it fascinating to see what words and phrases people are looking up.
Here are some of the recent searches I've seen so far:
The oddly specific:
a prueba de humedad (Spanish) - damp-proof (English)
sordid merchant (English) - 市侩 / shi4kuai4(Chinese - according to the two translators I use, this means 'Philistine' and 'money grubber')
What were the last things you needed translations for?