How about fictional characters? If WotC can bring novels in-house and republish them, they must own them.
If I write a novel about humans and elves and dwarves who are fighters and clerics and mages, with names like Mogsquith the Divulginator, or whatever I like, but use the online character builder to create and store their specifics, could WotC sue me for royalties for using those characters if I ever get it published?
Someone raised a similar issue on another board, only they were concerned that WoTC would take their character/adventure ideas and incorporate them into their own novels/published adventures.
For something like this to happen, some poor intern at Wizards would essentially have to go through over 40,000 "Tell Me About Your Character" stories. No one could do more than a fraction of that before jumping into the nearest sphere of annilhilation.
If you're really concerened, change the names of the characters in your novel.