All Free Dictionaries Project
Online project to build free translating dictionaries (e.g. English to Spanish) by allowing individuals to add and correct entries. Several dozen languages represented so far. Dictionaries can be searched online or downloaded. Includes links to other free dictionary sites.
Vesna Dictionary
Free online searchable Belarussian/English/Polish/Russian/Ukrainian translating dictionary that you can help edit. Site also may have documents about Ukranian literature and grammar, but they're all in Ukranian. Site may have ads inappropriate for young Web surfers.