I am a new user so the answer to this question might seem obvious.

The other night after I disconnected my iPod from iTunes I noticed another person's name under "Shared" on iTunes. This name is still on imy Tunes-so I am wondering how this person's name got onto my iTunes and is there any way to delete it?

I currently use an unprotected wireless network so I don't know if that has anything to do with it.

okay, the only thing i can think of is that maybe you have added songs from another persons computer onto your ipod??
are you using a network between your computers and other computers? or just your computer and the internet? a smart thing to do would be to create a WEP key for your network, this is just a password, that is something like 38 characters long, this would stop any future intrusions that may prove more sinister than just someone accessing your shared folders.
either you have put someone elses songs onto your ipod from their computer or your network has been accessed by an unauthorised person..... maybe get a computer technician to configure your network and security?