In Lion and Mountain Lion you can double-tap-3-fingers to look up word from dictionary. This gesture is so quick, clean and nice way to search for words, but it doens't support custom translations.
Eg. it supports japanese-english translation, but I would need finnish-english translation. Is there a way to add such dictionary. Or write custom function to lookup. Function could also use google translation api, but I don't know how to implement it.
Thanks in advance!