I just purchased one of these:
http://www.ebay.com/itm/190898629075

I figured I can't go too far wrong at 2 bucks with free shipping. It uses the TP4056 IC which is a constant current voltage limited charger, resistor programmable from about 50 mA to 1A, and can be connected to a USB port or a wall wart supply.
http://www.tpmicro.com/goods.php?id=47

Here is a review of the performance of this module:
http://www.candlepowerforums.com/vb...ment-on-Charger-module-with-TP4056-controller

I think it might be possible to put a diode in series with the output so that it might work with LiFePO4 cells. It should drop the 4.2V to about 3.5-3.7. I have some 18650 cells of both chemistries that I got for testing but this should be an easy way to charge them. I'm not sure I trust it enough to plug it into my main computer, so I might use one of my older spares (a Vista and a Win XP laptop).

It'll be awhile before it arrives, so I'll report on my own results.

The same company has other interesting stuff at good prices. I bought these:
http://www.ebay.com/itm/171122637723 (DMM)
http://www.ebay.com/itm/171122655356 (12V 5W supply)
http://www.ebay.com/itm/171122685439 (SPI OLED graphic module)
http://www.ebay.com/itm/171122637717 (Plastic hobby gears)

And from another company:
http://www.ebay.com/itm/261277770271 (SLA battery charger)
http://www.ebay.com/itm/261280214385 (Prototype boards)
http://www.ebay.com/itm/261280882626 (More Prototype boards)
http://www.ebay.com/itm/261277771952 (More hobby gears)