I charge everything with the iPad charger now, haven't had issues. iPad, iPod, phone, kindle, etc...
I think the very basic standard "powered" USB port on a computer does 5V x 0.5A for 2.5W.
Newer macs, and some chargers do 5V x 1A = 5W
The ipad charger does 5V x 2A for total of 10W (I think the 2011 MBPs can also do this too)
As long as it's 5 Volts, your gadgets are fine, and all the USB chargers are 5V. They will use as much current (A) as they need, for as much power (W) as they need.