I know it's often difficult to choose from what is a considerable array of stellar stories. However, remember you do not have to limit yourself to just one story per author, or even one story per category - you can nominate as many or as few as you like.
For ease of being able to find the pairing/section you wish to nominate a story in this post has links to all the individual nomination posts. You will also find full details of what can be nominated, but here are the categories in which you may nominate stories.
Full details of how to nominate can be found in the rules post.
Nominations close on 30th May 2010.