Many of my friends have recently acquired Macs, and they’ve been asking me about typing in Lithuanian on the thing. My preferred answer is to use the extended key options available to the US Extended keyboard layout (which lets one type in Lithuanian without switching out of a US layout).
My answer, however, is limited not just to Lithuanian, but to nearly any Latin-based writing system. The US Extended keyboard supports 19 dead keys for various diacritics that make it useful for writing in nearly every non-Cyrillic/non-Greek/non-Arabic language of Europe: Czech, Polish, Latvian, etc.
So although my video below is predominately interested in Lithuanian typing, I hope it’s clear that it can be used for much more. And forgive its clunkiness–it’s my first ever screencast.