Bikely
I stumbled across a site today, called Bikely. It’s got a fantastic implementation of Google Maps, allowing you to build and annotate routes you use. Obviously from the name it’s a bike site 
Here’s a sample of what you can do – this in my route home from work. It’s slightly different from the route in and I still need to figure out how to get around the CBD traffic if its possible
[removed the map as it was messing up my page layout, link here]
If you have a GPS device its possible to record your route and then upload the GPS file to the site. I don’t know enough about GPS to comment on this, but the site says it supports GPX files (GPS Exchange Format, GPS xml)
The idea of the site is great, if enough people participate form your area you could really refine your commuting routes and learn which roads are best to skip traffic etc. The site has a busy forum with what I would guess is a majority of activity focused on commenting on routes.
I see quite a lot of Australian routes on the site too. Nice