I love word games, but dont play many that require others to play with. I do play words with friends occasionally (far less since Zynga bought it, I was really annoyed about that). I'm also a scrabble player on my iPad. I'll look for you, Sue (I'm Sue too, but cant remember what my game centre ID is, I've had a couple)
Just looked at the others, I'm only into whats free, these days, Imangi actually looks a bit challenging, downloaded that. And here's another.
Wordly: theres only one level and the aim is twofold a) to get the highest score you can (you only compete with yourself) and b) to clear the board.