SEAsite Laos has the most resources on one website that I've found so far. I found the grammer notes useful, as well as many of the other Lao language resources on this site.
thailoa.net has information on the Lao language, including how to read and write Lao script and a good explanation of Lao tones.
Laos Guide 999 has a page of useful Lao phrases.
A collection of lessons for learning Lao
I couldn't find any good printable flash cards for learning the Lao alphabet, so I made my own.
Thomas Kallas has two great videos to help you learn how to read and write in Lao. His first video goes over the Lao alphabet and his second video discusses Lao Tone Rules. The videos are a little long, and I had to use the pause button lots, but they are both full of good information.
Branah has many virtual keyboards, including one for Lao. I tried about 3 different virtual keyboards for Lao, and they are essentially the same, but I liked this one slightly better than the others.
This is a blog post about using memory tricks to remember words in Lao (and other languages). I have 8 examples from the non-existent movie: Indiana Jones and the Nightclub of Doom.