http://gpsunderground.com
Community unlocked GPS maps for all brand name GPS with instructions how to use them, including all the Bluechart G2 Vision maps for Garmin products.
Update 6.12.12
So far I've downloaded with 100% success:
G2 Vision for my area
Garmin Lakes 2.0 (for the small stuff, G2 Vision doesn't seem to have smaller lakes)
City Navigator 2013 for all my friend's Nuvis