I've been learning Navajo (Diné bizaad) and Irish (Gaeilge) languages recently and have been struck by some similarities between them. The most striking feature they share is that both languages have personal forms of propositions.

I started learning Irish at the Oideas Gael language school on the beautiful Donegal coast (check them out at http://www.oideas-gael.com/en/ and @Oideasgaelbeo). I've been leaning Navajo with Duolingo and have found @daybreakwarrior 's content really useful and informative.