My choice of storage for a WIP is largely determined by the size of the finished block and how much progress I have made. I tend to store piles of blocks ready to be assembled into tops in scrapbook containers stored in a cupboard. These are great because the fit blocks up to 12.5" square and have a decent depth to them. Pastry containers are also good for slightly smaller blocks (but I forgot to take a pic of my stack of those).
I also have a number of WIPs stashed in clear containers within drawers. I like these particular containers because they have clear lids, which make it easy to see at a glance what is inside. I tend to use the smaller ones for storing projects where I have cut all of the pieces but haven't sewn the blocks.
For smaller projects I like to use document wallets - they are cheap, see-through and great for storing printed instructions together with fabric/blocks. Here are a few from my collection.
For projects with a lot of small pieces I like to use serving trays. I have a small stack on them under my sewing bench
Another place where WIPs tend to accumulate is on the cutting mat. At the moment I have three projects on the go. I find little baskets helpful for storing fabric pieces - it's easy to stack them up and pop them off to the side when I need to cut something else.
Finally, I have a lot of WIPs stored in large containers, using a combination of document wallets and baggies. For example, a big tub of Christmas projects I started (but didn't finish) last Christmas.
I've listed the details of the numbered WIPs below. Hopefully I've be able to knock off a few this quarter and free up a bit of storage space for other things (like more fabric) :)
1. Ripples blocks from this year's bee.
2. Bonnie and Camille log cabin blocks from a block swap
3. Sampler blocks from the quilt block cook book sew along
4. Milky way sampler blocks
5. Bee-sewcial sampler blocks
6. Ombre gems blocks
7. Homeward bound blocks
8. Garden snails blocks
9. Fracis firefly blocks
10. Strips for a improv tumbler block quilt
11. Strips for a simple patchwork bay boy quilt
12. Scrappy trip around the world blocks
13. Swoon blocks
14. Cut pieces for a Hazel hedgehog mini
15. Cut pieces for a spell it with fabric numbers mini
16. Strips for a DS crazy coins cushion
17. 3.5" squares for a DS quilt
18. Basted, but not quilted, charity baby quilt
19. Another basted, but not quilted, baby charity quilt
20. A half-pieced baby charity quilt
21. Baby quattro quilt
22. Moxie mini quilt/playmat
23. Wild goose chase quilt
24. Glisten quilt
25. Strips and squares for a pineapple block quilt
26. Background pieces for a Geode quilt
27. In progress baby bedding
28. Hand-pieced hexi panel for stocking
29. Pieces for a Flurry quilt
30. Christmas economy blocks
31. Selvage strips so a selvage tree mini
32. Pieces for a patchwork forest mini
33. Jacobs ladder quilt.
34. Quilted stockings for my family.