There is the parody law. That is, if you make it known that you are not related in any way to Herr Disney and his satanic cult of minons, then you can do whatever you want.
The lawyers' first claim is that you are misrepresenting their property as that of your own creation and making money from it. The weak who know that claim is bogus will cave in and the Disney monkeys know it. Fight back and make them look ridiculous while doing it, they get very soft and defensive very quickly -- especially if you deal with children.
There was a incident years ago where a pre-school near both Universal Studios (FLORIDA) and DISNEY WORLD had painted DISNEY characters on their walls. DISNEY FLYING MONKEYS swarmed on the pre-school owners and threatened them with closure and complete legal bankruptcy for daring to entertian children with Mickey Mouse. -- The UNIVERSAL STUDIOS hear about this, sent their painters to adorn the pre-school walls with HANNA-BARBERA characters FOR FREE and made it a HUGE media event, complete with photo ops of costumed characters playing with the children. DISNEY was made to look bad and went to work right away trying to kiss up to the pre-school.
I am also a Disney attack survivor that sent them packing too. I am a caricature artist who was always requested to draw girls as little mermaids. A DISNEY MONKEY LAWYER saw my work at the BUENA VISTA MALL and threatened me like an immigration officer. I stood up to him, towered over him, and sent him running in fear.
A Balloon Artist friend of mine volunteered his time to entertain children with cancer at the local hospital. One of his specialities was making balloons looking like Tinker Bell and Mickey Mouse. A Disney lawyer who attended the hospital for his yearly head up his assendectomy saw the balloon creations, investigated my friend's business and threatened to "ruin his life" if he contnued making tinker bell balloons for for sick children. Word got out. He still makes themnow with the Rat #*$!'s blessings.
HOWEVER, if you use on a product you are selling, their icon that is a direct copy or reproduction to the letter of one of their properties, they have all the evidence to prove to a judge that you are misrepresenting your product as DISNEY-made. That's where you get your butt handed to you.
BUT, if you're using a Tinkerbell on your MYSPACE because you just like the character and you have no ulterior motive to make a profit from it, then don't worry -- and laugh at the Disney monkey who beats his chest and makes suing noises. He's full of hot air and he knows it.