Well, and this may come as a shock to everyone here, be warned... but... I really like the numbers 4, 5, and 6

<- (cough, cough)

Saying that, here are some of the cool ids I've gotten so far:

Veemooth #64446
Rootax #65400
Fluffpaxa #44565
Fluffpaxa #64445
Iguzzle #50646
Pydeer #60504

And my 2 personal favourites even though they don't exactly follow this theme (but are still super cool):

A velibolt with #22244 and my first pixpet ever, a Parrogrine with #946! So close to that perfect number!