Telstra - The page that is hit most as far as looking glasses go (for obvious reasons)
Optus - Probably one of the best looking glass pages for Australian networks
connect.com.au - Another good referece. Identical to the Optus page now (has changed in the past few months!)
Pacific Internet - Pacific's page is a little different. A direct link to their NOC page, with the looking glass off it.
Worldwide looking glasses - If you want to look at other networks worldwide
Interactive traceroute/looking-glass - Much like the MX verifier.