Thanks for the suggestions. I decided to do an update and do some changes. Now the blocks bounce with more delay one between each other. Someone also told me to try to expand the blocks only horizontally, and so I did. It looks more "realistic" now, imho. The shadows, while it sounds like a good idea, since I prefer to use transparency, and the message boards I use this on have different backgrounds, they'd look a bit bad in the ones with dark BG.
Update 2: Argh, the edit option will refuse to work. If you want to check the edited version: [link]
Well, while experimenting with some stuff, I came up with this little animation. Not much to say about it, just that I did it for using it in several message boards.
pixelled in Paint Shop Pro, animated with Animation Shop. It has 30 animation frames and 10 colors were used.