Giota Beag – BBC series for learning Irish, all free and still one of the best introductions I have come across.
28 podcasts giving an introduction to basic Irish
Links to various resource collated by peig.ie
Buntas na Gaeilge – Scroll down to the bottom of her profile page to download the pdfs and audio files for two textbooks aiming to teach Irish to adults who are learning it for the first time.
Free Irish audiobooks from LibriVox (not many there yet, but somewhere to start)
No Béarla TV series (on Youtube)
Like him or loathe him, this is fascinating – Manchan Magan attempts to travel around Ireland without speaking any English, only Irish. I did feel that he chose his places in order to get the response he was expecting at times (e.g. visiting an area known for not speaking Irish and ignoring a nearby area where Irish is spoken). However, still an interesting watch which gives you some exposure to Irish (with English subtitles)
I really like this, especially because you can click next to most words to hear them pronounced in the three main dialects of Irish (Ulster, Connacht and Munster). Irish pronunciation is tricky for beginners so this is an extremely useful feature.
Useful for every language, not just Irish.
Other lists of resources:
Benny Lewis’ Fluent in 3 months Resources for learning Irish
Donovan Nagel’s resource list (including reviews of several popular textbook options)
Robert Kaucher’s list and advice
RTE’s list of resources and links
Advice on learning Irish from Frances Mulraney