I actually signed up so I could answer this question. I'm really glad someone posted a link to the Post Punk Kitchen since thats the site that has helped me the most. There are a lot of great recipes that are vegan already or with small changes. A lot of wacky cake recipes are vegan and wonderful, even just sprinkled with powdered sugar. You could also make any sort of fruit by and substitute the butter with margarine (I highly recommend Earth Balance since its one of the only vegan butters I've tried that mimics butter in baking, especially in pastry - plus its available in sticks so its easy to measure). The chocolate tofu pie is another great idea, as well as peanut butter chocolate pies that are easy and taste like giant peanut butter cups.

Here are some recipes:
Peanut Butter Chocolate Pie
Wacky Cake (Chocolate Cake)

I have a ton more recipes if you had something in mind. Just keep in mind that not all margarine is vegan, some people are particular about sugar (cane sugar is often processed with bone char, but many generic sugars are beet sugar and are completely vegan), if using something processed read the label for things not on the allergen list like gelatin, and make sure to eat some of the batter