This could be better than your browser's bookmarks. While I appreciate the simplicity of it, it's too simple as it is now. The potential benefit here is in hierarchy, which bookmarks generally lack. How about this:

4 links at the big 128 x 128 size. The sites you check every session.

8 links at 64 x 64. The ones you use pretty frequently.

16 links at 32 x 32.

And heck, maybe 32 at 16x16.

I would use that.