From Center front clockwise:
Post-it Grid Notes: 2 pads of 50 4" X 6" sheets, $3.63. Quilters use grid paper to figure out patchwork designs; I know some writers prefer grid paper for writing, drawing maps and what have you. I like the roomy size of these notepads.
Post-it Label Pads: 100 1-7/8" X 2-7/8" labels in neon pink and green, full-adhesive backing but still removable, $2.99. Often I reuse storage boxes and containers for various purposes from year to year, so removable labels are more convenient. These would also come in handy to mark the front of binders and folders when I recycle them.
Post-it Label Roll: 1" X 700", neon green full-adhesive backing but still removable, $3.14 (clearance price). If the label pads are too short, I can use this to cut the length I need.
Post-it Note Tabs: 20 2-3/4" X 3-3/8" tabbed notes with removable adhesive, $2.69. These are extremely cool. Not only are they tabbed but they have a small lined section for notes. If you hate marking up books, manuscripts or other paper documents during editing these would give you some writing space and mark the page you need to return to (I'm going to use mine for galley corrections; will eliminate the need to make two piles of pages.)
And finally, not Post-it brand, but still neat:
Mead Pagemarker Clips: 24 two-sided paper tab-backed clips, $1.98 (clearance priced). I thought these were a clever spin on the bookmark, as you can write a word or two on both sides and then they'll work as tabs or tabbed dividers without having to put in a whole tab page. Good for marking passages in research books for easy future reference.
All found at Target, which often has much in the way of Post-it coolness.