Try closing LimeWire, Internet Explorer, and any other known net-enable apps and waiting 2-3 minutes. Then try checking if you still get incoming requests (netstat is good for this). If so, you may be getting hacked. Chances are slim tho, unless you're broadcasting a web server, or running WindowsXP with no security patches, or something like that.

Gnutella is based on having a number of IP's connecting to you (or you connnecting to them). If you are an ultrapeer, more than 50 IP's may connect for a while, but only a few if you're a leaf node. KaZaA is the same. It's the result of distributed P2P, and is what keeps it from being put out like good ol' Napster.

And for sure being a little paranoid doesn't hurt.

Cheers