Today I spent a significant amount of time using the freely available Cisco Network Assistant. This tool allows you to probe your [Cisco] LAN and identify the topology. This proved very useful as although I had a rough idea of how the network was wired, the software highlighted a couple of issues that I need to resolve. Once identified, you can directly interact with the devices, renaming switches, creating VLANs, enabling and disabling ports. Really, really nice - especially for the price.
The reason I'm doing this is that I want to get the topology accurately mapped before starting my Nagios deployment for network monitoring.
The only downside was discovering the SFP modules we bought for server interlinking were not "Cisco Compatible", so we'll have to spend double to get the same thing!