I really like the first 2, the rest..I don't care too much for.
I myself is experimenting in photoshop.
I've made signatures before but recently I actually started getting interested in getting a more vast knowledge of photoshop editing.(Using c4d's and using stocks as backgrounds and such)
the one with the movie was made in photoshop and later the movie was put in with imageready and after that again edited with photoshop to make it look like its behind the signature (so it isnt just a square)
and its possible to make avatars with movies/ moving parts in it but the site should also allow .gif files as an avatar