All of these things have to be labeled, and we love Mabel's Labels:
At the beginning of kindergarten, I bought a Big Kaboodle combo pack for each boy. They are pretty pricy but we've been using them for 18 months and still have a very large supply. We keep them in our junk drawer downstairs and whenever something new is sent to camp (or school), we slap a label on it.
To me, what really sets them apart is their ability to stick to fabric and not come off in the laundry. One boy (let's call him "N") left his swimsuit at the big YMCA last summer. The lost and found had hundreds of swimsuits, mostly from Old Navy. I found four sets exactly like N's and was able to identify his by the labels on the tags.
(Reusable snack bags by The Umbrella Girl. Lunch box from Lands End, which fits the Pottery Barn Kids bentos perfectly.)
(No compensation for this post, we just really really love those labels.)