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.
Goethe Multilingual Exercises
100 free online vocabulary tests to/from 10 different languages. Not interactive - one page has fill-in-the-blank phrases, another page has the solutions.
Browsable (not searchable) Indonesian-to-English (and vice versa) dictionaries (using transliterated Indonesian characters). From Asiamaya.com.