On top of this, I'm actually putting the skill challenge into my 3.5 "Holy Crap! Giants!" game, where there are no handy guides to expected skill use DCs by level and I have to make my best guess based on what seems reasonable and what I know the players have. Unlike 4E/SWSE, skills don't automatically progress with level in 3.5, meaning that they're super-swingy. A tricked-out rogue can easily have +10 on multiple skills at 1st level ... a 10th level fighter is lucky to get +10 on anything except possibly Climb or Jump. So I have to pull DCs out of my hat and make sure I allow "automatic" successes in ways that don't require a DC 30 Craft: Basketweaving check, for example.
Oh well, I knew the job was dangerous when I took it! Besides, it's the players' job to tell me how they're useful, not the other way 'round. Although I've written up some possibilities, I'm looking forward to seeing what they can come up with. If nothing else, it's a very different sort of activity from the usual hacking-off-limbs and blowing-up-hordes that happens Saturday nights 'round here.