I've recently been working on the branding for the online running support group Run Mummy Run. It's been a great fun project to work on. When Leanne asked if I could do something like a word cloud for their banners I jumped at the chance. I like word clouds, but only done a christmas tree one before. There's a lot of bad and good examples around on the internet.
My advice is 'don't try to hard.' Keep it simple, limit your typefaces and colours otherwise it can get messy.
I used the typeface Rockwell for this to match the logo. Variety can be achieved by changing the weights, light, regular and bold. And picking 2-3 colours or tints.