I like anacharis and stem plants, most are low light needs plants. They're pretty easy provided the tank isn't one of the higher temp tropicals, I noticed mine start having trouble around 80F but do fine in 78 or lower. Anubias plants are pretty good, about medium light needed. The Anubias Nana's are the smaller ones, the others can get pretty large. I had one in my 55 gallon that gets tall enough to stick out the top if I don't clip it.
I'd go with those. Stem plants are easy, you can make them grow in odd directions or even spiral, or clip them and replant the clippings. That's the only thing they really require, clip and replant if you want more. =)
Java and Willow Moss is pretty good too, about low to medium light requirements.