What to do when iPad is stolen
The first thing you should do is report it, having the serial number by hand (you can find it on the original box). While the procedure of handling stolen goods might be different in other countries, it's not unlikely police bumps into a batch of stolen goods and will try to get these back to the rightful owners.

As for tracking, if you had a Gmail account set up, you could check Gmail's connection logs (available from the bottom of the web interface), to see the IP addresses connecting. The same goes for other "cloud" services which allow to see a log of clients, like Dropbox.

Whether the IP address will lead you to the thief is questionable, but it could give you a broad localisation and you can always pass this information to the police.

If you had an iPad with cellular support, it is technically possible to be tracked by IMEI number, but depending on legislation/others, your carrier might not fulfil these requests without the necessary warrants.

Apart from tracking though, the next thing you should consider is safeguarding your data as much as possible. If your iPad was not password-protected, you should change all passwords of any online accounts configured, but please note this might prevent you from seeing access log as described earlier.