Cisco CNA 5.0 & Cisco CCP 2.7
While I wouldn't mind specializing doing Cisco-only work, I am not Cisco certified (officially) and therefore should not be listened-to regarding the following. I'm surprised how many Cisco certified professionals I work with have ever used CNA or CCP. Both programs are free, by the way. The CNA shows all corners of the device displaying tons of information, a lot of which real-time. The CCP lets you create config file templates. The really neat thing about CCP is if you don't know syntax, you can set the option in the GUI and copy the output, very helpful.