Here in Montgomery County Maryland, work is slated to begin on the Inter-County Connector (ICC) that will connect Montgomery and Prince George's County. This road might have been worth building if it landed further north on I95. Think BWI airport access for folks and businesses in the I270 corridor.
Take this a step further and extend I370 to Rt 28 in Sterling VA. Finally, another river crossing that would be used by millions and reduce beltway traffic. I'm not sure why Montgomery County is so scared about building another bridge into Virginia. Are they going to take all our precious jobs? Get a clue they already did. All the software engineering jobs migrated to the Dulles corridor over the past 10 years leaving us with Biotech and government jobs. While these are good jobs, having 3 airports withing 40 minutes of Gaithersburg (non-rush hour) would be a huge benefit to business in the I270 corridor.
And don't give me any crap about protecting our farms in the western part of the county. Better to build a road though them now before they too are sprawling suburbs. :-)