Yahoo Maps added drag and drop customizable routing, among several other improvements to the site. There’s more discussion and explanation on the Yahoo Local & Maps blog. Google has a similar feature. Below are some screenshots of the new capability on Yahoo. Additional feature upgrades on Yahoo Maps include photos and reviews in Ajax pop-ups that appear when you mouse over individual business pushpins on the map.
Yahoo directions from San Francisco to Yahoo HQ in Sunnyvale, CA:
And now the customized route, where you’ve dragged the original route off the 101 freeway and over to the 880:
A window in the lower right allows you to compare the two routes by time and distance, which is a nice feature.