Mavry has a shelf in the living room since she doesn't have her own room yet. Her shelf is the bottom level of our coffee table. I got some small shallow baskets from Goodwill to organize her things. I try to rotate her toys so that she only has a few out at a time and so that her space is kept fairly simple.
I get jealous of simple little spaces like this or this, but we are glad to have the space that we have for now. (We are still looking into places to move and are even considering moving in with another family to a large Victorian house. An exciting prospect!)
When we put Mavry on the living room floor, we put her near her shelf on her back. She will sometimes stay on her back to play with her toys or kick at the mobile (Colin recently hung the puzzle ball from the tripod), but usually she will roll over to her shelf and go for the baskets. She spends a little time chewing on the baskets and then pulls one off the shelf to look at what's inside, then she chooses a toy! It's great to watch her independence in choosing what she wants to play with.
Since she started pulling her baskets off the shelf, I have taken the heavy set of Eric Carle books out so she doesn't injure herself. She still has the three baskets, but each one has only a few things in it to make her space more simple. In the Montessori tradition, children have low shelves with activities organized in baskets or on trays so that they can choose an activity and know how and where to return it when they are finished. Sometimes I will clean up her area when she is not there, but I try to return the toys or books to the baskets while Mavry watches and I describe to her what I am doing.