I themed my room for the book, The Dot. So I have dots on the walls, for curtains and table signs. I used dots on the front boards (wrapping paper). The table signs are the dots "framed in swirly gold" frames. All of my chairs have colored electrical tape spirals on them, 4 colors per table. These help me to select helpers during class, and a happy bonus, they don't come off or get picked at by little fingers.
I decide to keep my desk this year in the storage room to give me more space to move around. Especially, since I have a SMARTBoard!!! I am using the row of milk crates under the board as step stools for the smaller folks to reach the top of the board.
The valance over the window are paper covered cardboard pizza rounds from our local Imo's Pizza. Parents can be a great source of materials, especially recycled items. The lamp are IKEA, they are a great light source when I shut down the overheads for working at the SMARTBoard.
The back my room had a full wall bulletin board, until they turned the room into a 4th grade. Then they put a coat rack in the middle of my board. So to disguise it and stop head injuries from students running into it, I made a faux shelf from pink construction foam and covered it in butcher paper. It is light weight, cheap and looks good. The green tape seen on the floor is tape I get from the PE teacher for marking floors. I use it to set up no go areas for students. In this case we create a "pond" around the demo table, to stop crowding around the table. This inevitably ends up as a shoving match and students shaking my table. I create a line they cannot pass, which spreads them out and keeps them off my table.