I do it the old-fashioned way. I keep a running tab on a piece of paper, and I use a pen to write in the # of points I used for a particular stay, the confirmation #, the person I spoke with and the dates of travel. It ends up looking something like this (note all names and point values are made up):
200 points Sept 1, 2004
-44 points for 1BR OKW Oct 1-3,2004,spoke w/Sue res#2223344
___
156
-78 points for 1BR BCV Jan 5-9, 2005 spoke w/Bill res#55667788
___
78
-65 points BWV 1BR May 3-10,2005, spoke w/Mary res#9988776
___
13 points banked into 2005 Use Year
And so on...
This sytem has always wroked well for me. It's simple, and I have never been "off" with points used, remaining, banked etc.