USB Charging reduce/consume charge-cycle

USB Charging for your BB
www.blackberryforums.com/general-blackberry-discussion/214689-usb-charging-your-bb.html

Stop USB Charging for Mini Ipod
http://forums.ilounge.com/showthread.php?t=45350
Interesting comments:
...a lot of smaller quick charges are much better for LiOn than occasional large charges
...buy a powered USB hub (the kind with an external A/C adapter) and use that to do your iPoding. If you don't want it to charge, just unplug the A/C adapter.

For Windows Mobile(?)
Registry entry to control USB charging:
[HKLM\\Drivers\BuiltIn\Battery\EnableUSBCharging]
if EnableUSBCharging = 1 --> Phone will be charged when connected to a USB power (laptop, etc.)
if EnableUSBCharging = 0 --> Phone will not be charged

Related
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Is it possible to plug phone/tablet to computer's USB without charging it?
Google: connect|plug|attach phone|tablet|gadget to usb without charging

Is it ok to keep iPhone in charge all day long through USB port or power adapter?

In some (older) cases, USB devices can only be charged by computers with specific drivers installed
source: How USB charging works, or how to avoid blowing up your smartphone

For a start, every charger or socket has a max amperage — usually between 500 milliamps (mA) and 1.5 amps (A). In general, unless it says otherwise, your laptop and PC are probably outfitted with 500mA sockets (unless they’re USB 3.0, in which case they’re probably 900mA). The max amperage of a wall charger varies, but can usually be found written somewhere on the charger — generally it’ll be between 0.5A and 2.1A
...
It is through negotiation that your device actually decides how much power it wants to draw.
source: How to charge your smartphone and other USB devices as quickly as possible