I'm in the very midst of exam revision (horrible) and grasping the last straws of sanity by using this difficult time as an excuse to stock up and use some rather nice stationery.
One of the things that is coming in for a lot of use is a pack of Exacompta index cards, 100x150mm, in plain white unlined. Since I have to memorise a lot of nasty equations and ideas, these are very useful for drawing out the main tricky concepts that I need to remember. They are very smooth and satiny and a joy to write on, quite FP friendly. I note that ink takes a little while to dry on them, but not overly long. Mostly, I am appreciating their silkiness and the way that there is no feathering or bleedthrough. I found these also to be quite reasonably priced, and went back and got another pack of 100 as I'm almost done with my first pack.
In summary, those looking for FP friendly index cards should look in this direction. Ver' naice.