Whew, today's challenges were a little tough, but I've done all 15 to date.
kaos_lord - I love Jelly Blobs, too, I used to spend lots of time playing that game when i was bored! Now Faerie Bubbles ... I don't know why I'm so horrible at that game, but it took me several times to get the score of 400.

Argh, Water Horse ... the best tip I found is to 'shrink' the window down to 50% (bottom right hand corner), and don't go too out of your way to catch the fish - this helps greatly.

Edit:
This petpage has a list of the prizes on it:
http://neopets.com/~robacer