Is it possible to damage the 6700 by using just any old usb charger? I had this
and it seemed to work fine, but I dunno if I'm doing any damage to the unit.

I've been using a similar one (with the retractable cord from Emerge Technologies) for a while with no issues other than that the phone occasionally will refuse to charge for a while (5-10 minutes) - that problem is not limited to this charger and seems to be more common with AKU3 roms. It seems that the charger itself shouldn't cause any damage as long as the output voltage is within the USB spec.

As long as it puts out 5v and at least 500 ma, you're ok. I have several chargers that I use in various places and only 1 of them is the factory unit.

I agree with everyone else. I currently use a retractable USB at home and a 3in1 at work FYI.

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http://weedahoe1.no-ip.info VZW xv6800 ROM 3.56, Radio 3.42.50, PRL 51056, PRI 1.35_002