why dont you do something special instead like a special outing or meal, if you buy him something and he hasnt bought you something you may get upset ?
i would get a card or maybe just write a letter saying how happy he has made u over the past year etc.maybe a small box of choccies and if he hasnt got u anything say i bought these for us 2 share to celebrate 1 year 2gether
a good idea is to leave a note on the table when he gets home from work to go up to the bedroom, put some saucy undies on put a big red ribbon around yourself and you can be his gift he has to unwrap