MN/DOT makes freeway travel time data available in a nice format, so I mashed it up with Twitter to tweet travel times on the various roads around Minneapolis and St. Paul at
traffictweeter.com. Travel times are tweeted every ten minutes during rush hours.
Maybe you can use it to determine a less-congested time to leave for work or home, and save yourself some time sitting in traffic.
I'd like to expand it to other cities. Let me know if you have a city you'd like to see added, and I'll investigate to see if the data is available.
Smooth driving,
Matthew