"How do I find a Cisco serial number remotely through the command line?"

This is one of those frequently asked questions that I see over and over. So, here's the quick and dirty answer:

You can find Cisco serial numbers from the IOS command line by using the show inventory command.

This is good news for all the folks out there that have needed to collect this information remotely for service contracts, TAC cases, etc. Unfortunately, according to the documentation, the show inventory command was introduced in IOS version 12.3(4)T. I can tell you personally, though, that I've run this command on some versions of IOS 12.2. I suppose your mileage may vary.