"Fire words" should hold you until bookworm comes out.
Fire Words is more like the Action version of Bookworm. It's nice, and it
looks like Bookworm, but one of the things I love about regular Bookworm is taking my time to craft long, difficult words. You can't do that in Fire Words because the blocks are constantly burning -- not just as a result of creating short words.
WordsWorth is a better comparison. I also just picked up "Words - English" by Mobilutions, which has a similar feel as well.
Right now, Scrabble is actually keeping me occupied, but I'm eagerly waiting for Bookworm to arrive, which I hope happens within my device's lifespan!!