A confession... the whole teensy-tiny index-card thing bemuses me. Oh, I use plenty of index cards. I use them when I'm writing, and put scene notes on them and shuffle them about to sort a plot out, but I use 3"x5" versions for general scenes and 4"x6" for major plot-point scenes, and different coloured ones for different plot strands. But the small ones that are all the rage? I don't really know what I would use a whole box of them for. They're certainly too small for plotting.
However, Nero sent me some dinky Dapper index cards to play with and they are rather nice quality. They are 2.5" x 4" with dot-grid, graph, plus-grid (the dots are +), or lined on one side, and they are all plain on the other. The card is nice and thick, and as Scrib noted last week, suitable for all kinds of pen or pencil. The cards have rounded corners and are immensely tactile.
So far, I've been using them like sturdier, non-sticky versions of Post-It notes and paperclipping them to other things - a note on the calendar next to my desk, reminding me when the pop-up Post Office might appear in the village, or which random days the library might open - and they're working pretty well for that. I have a recurring thing I have to do at the end of every month and a sticky note often falls off my diary, but now I have one of these cards clipped there, ready to remind me of the task and then be moved to another month when done.
Stu uses them as a portable note-taking system and also uses one a day to indicate his "three most important things". I know other people like to store quotes on them, or to use them as a free-form, unbound journaling system. Educationally, there are lots of uses for small cards, from flash cards, to creating a timeline of facts and a million other things. I may well put some Fair Isle knitting motifs on them and keep them in my knitting box.
The small index cards really are very sweet. They're a little smaller than the Foglietto versions, but would fit in the Foglietto storage boxes, should you wish to keep them for posterity.