Boil the frog , go from one artist to another it will filll in a playlist. Pretty cool.
According to the website itself: Boil the Frog lets you create a playlist of songs that gradually takes you from one music style to another. It's like the proverbial frog in the pot of water. If you heat up the pot slowly enough, the frog will never notice that he's being made into a stew and jump out of the pot. With a Boil the frog playlist you can do the same, but with music. You can generate a playlist that will take the listener from one style of music to the other, without the listener ever noticing that they are being made into a stew.
I'm using it right now for the first time, so I can't really comment on the validity of their claim... but it's certainly a really damn cool idea. I'll give an update if my "from Maya Jane Coles to Boris" mix actually worked out.