I keep reminding myself it's too early to start seed (the young plants would outgrow my windowsill/coldhouse space before it's warm enough to set them out). My coldframe house doesn't need rewrapping or a new paint job this year- it seems to have held up very well. So when I feel antsy I browse through the seed catalogs, always find more things I want to try than I have room for! Repot a few of my houseplants. And then organize and clean my gardening stuff.
Here's a stack of re-purposed plastic trays. Deeper food containers with a lid are the best for starting seed. I cleaned them up and tossed a few that had cracked, were made of weak plastic, were too shallow to be really useful or had lost their lids.