I used to use a shoebox cover to hold all the stuff I didn't want to forget before leaving for work (e.g. wallet, cell phone, keys, etc).
Last week, I was at the Container Store and found a great do-not-forget-me box. It's a clear acrylic desk organizer, about 9" x 9" square and with 3 partitions. Here's a photo of it in use:
It's working great so far. The partitions let me divide stuff into finer categories: a) must take with me every day, 2) maybe take with me, 3) rarely take with me.