G+: This is a wonderful tool

David Coles
This is a wonderful tool. It's the most comprehensive network testing tool that I've seen in a long time. Basically it has the philosophy of trying nearly everything possible - it's not quick but does give you a very comprehensive view of someone's connection. There's even a standalone client (for browsers who hate Java) and generates nice little result pages that can be shared.

ICSI Netalyzr

Rae Yip
Amusingly, one of my friends used to work for ICSI. They've got a cute little office.

David Coles
They're doing excellent stuff. :)