Well, I'm assuming you are asking this question to find out info on OP.
Based on that, what info do you have already?
If OP is being contact by your WS on your home computer, install a keylogger program to monitor the computer usage. That should capture a ton of information.
If you have any other information about OP (full name, address, IM/chat handle/address, etc...) then try doing a search on the web with various portions of that information (like do their address, or do their name and city, or name and phone number).
If you know of any nicknames or usernames that this person uses, try looking up those on the internet as well.
Try hiring a private investigator.
Another common tactic used by PI's (and scam artists, so warning...I am NOT responsible for any legal issues around using this...): Take whatever personal information you DO have, and use that to 'phish' for additional information. For example...call the driver's license bureau posing as OP, claiming to have lost your license (wallet/purse stolen, whatever). Give OP's name and address...and while you're asking them for 'advice on what to do from here', chat up the person on the other end, and ask them if they could give you the DL # so that you have it in case you're asked for it...or ask them to assist you with the VIN of the vehicle that is registered to OP (I'm looking to sell it, and wanted to do a search online, but didn't feel like walking out and looking for the number). Try calling the local utility companies with the name, phone number, and address. Tell them that you've had some issues with inaccuacies in your account info, and would like them to verify contact information (such as phone number, address, email address, etc...). Heck, pose as your WS and tell them that you're helping out OP by making these calls for them!
If you're very personable, you could likely get a lot of information this way...but...again...THIS IS LIKELY SOMETHING YOU DON'T WANT TO BE CAUGHT DOING.
It took me less than two hours with nothing more than OM's first, last name, and middle initial, combined with his work number from my wife's cell phone bill to get his home address, home phone, direct work extension, work address (to include cube number) and work email address. Another 20 minutes with a chatty personnel assistant gave me the information on what vehicle he drove, and that he normally walked to work.
Hehe, the things I learned before I became a normal person! <img src="/ubbt/images/graemlins/smile.gif" alt="" />
