If there is no tracking software installed on your computer, then there probably isn't any technology solution to getting it back; however, here are a few possibilities:
- Have you installed any sort of remote-control software, like LogMeIn?
- Do you have a Dynamic DNS client installed? You probably don't, but you never know...
- Do you have a gmail account which you are either logged onto in the browser or have setup to download mail via POP or IMAP? If so, you can check Gmail's acess logs and possibly get the IP address of where your computer was last seen.
Any of those methods might help you find the IP from which the computer was last accessed. If you can get the IP address, you can figure out who the ISP is, and the local police department can contact them and ask for where that IP corresponds to. Most ISPs will cooperate with these sorts of requests; even if they don't, the police could subpoena them for it, that would just take a bit longer.
You should also report this to the police immediately. Tell them the serial number of your laptop; this way, if the thief tries to sell it, there's a possibility that it will be on a reported-stolen list and the seller may be caught. It's not likely, but it's a possibility.
Finally, if you have insurance, contact your insurance agent right away to report that it was stolen. There's a chance they might be able to cover some of the cost of replacing the laptop if it can't be recovered, and might even have suggestions for how to get it back.