I'm trying to relay a wifi connection from several blocks away (using a biquad antenna) to another location.  Ideally, I'd like to be able to run a local wireless network, and use the connection attached to the antenna as the internet uplink.  So...

Local Network -> Wireless Router -> External Wireless Signal

Do the experienced folks here have any ideas as to whether this is possible?  I know I could set up a separate desktop box to act as the internet gateway, but if there's any way to do this with embedded hardware, it would be much more efficient.

-Thanks
CptOatmeal