dvideo - once you start "seeing" how these things are constructed and manipulated, you will quickly see how you can make your own and then save them as your own preset, veggies to be re-invoked at a later stage.
Once you start seeing the philosophy behind Vegas, this is a remarkable platform to be creative on!
Here is one that I've started to use lately that is simple but extremely natural and kinda optical . . . Scott's Fabulous Website for Cubes Transition and SMLuminance. This last one you invoke your own "shapes" as the transition path: Diamonds, Squares, but if you had a bmp outline of a Tree, Dog, Cup .. or whatever . . I've recently used LETTERS as the transition path, it works! PLUS he's got the famous CUBES transition too! Here yah goes: http://www.endor.demon.co.uk/