Maple (have up to v7, now v9.5): knew a little once; learning it.
Mathematica (up to v4.1, now 5.1): seen bits and pieces; want to learn.
Excel: you'd think, wouldn't you?
Thanks to miyeko for finding the solution to my charting problem. I was trying to make the first selected column, the experiment time in half hour increments, the independent (aka Category or X) axis. Turns out there is a Series tab in the second dialogue window of the Chart Wizard in MS Excel 10 and 11 (Office XP and 2003).