NeoPets

To access the secret laboratory, first you need to have the nine pieces of the secret laboratory map in your inventory. Although they all have the same item name ("Secret Laboratory Map"), they all have different images, and vary in price from around 20,000NP to about 250,000NP.

Once you have all nine pieces, visit the following link to obtain access to the lab ray:

http://www.neopets.com/games/treasure.phtml?type=lab

Click the button and you will receive around 10,000NP and have access to the lab ray.

Once a day, you will be able to zap one pet at the following link:

http://www.neopets.com/lab2.phtml

The lab ray can change your pets stats (including gender), both increasing these stats and decreasing them (although it will never lower your Hp), change species and colour. There are lab ray specific colours, such as robot and sponge which cannot be obtained in other ways.

Expect to pay around 1 million NP (based on current prices) for all nine pieces. I think it is worth it.