The First Grade Sweet Life: Reading Centers--pattern block sight words! Get some templates, write words on them, and the kids have to play in pairs--correctly saying each word (and using it in a sentence?) before they can cover it. Also for math shapes!
This has easily been the most popular enhancement so far this year! The children have affectionately named it the pom-pom game. You will need some cups (I got these funky looking monster ones from the pound shop), a marker pen.