I don't think free apps show up on your account. Try loading them from the market webpage on a computer. You may find some of them there. I have had this issue when switching devices. The paid apps appear in "my apps" and a lot of the free ones have disappeared, and I have to remember what they were and search for them.
I'm waiting to get mine back - should be in the next couple of hours.
I used my ThunderBolt and took pics of my XOOM screens before I performed a factory reset. I just wanted a reminder of what apps I had installed and where I had them. Now I'm really glad I did this after reading some of the comments regarding re-installing apps.
yeah i used the SDK and did screen shots of my apps, but this is my second xoom when i got it ALL of my apps were in the market all I had to is push install. when i go to them in the market on the browser they all still show installed. I bet this is a bug with the new market.