Sonar is a submission-tracking tool for short story writers. After entering brief details for each story, you can link them up with a market when you submit to them. When the work comes back (or is sold) you update the submission. Using Sonar you will never send a story to the same market more than once and you can ensure that none of your work is gathering dust. You can bring up a market (e.g. a print magazine) and see a list of everything you've sent them along with the results. You can bring up a story and see a list of every market you've sent it to.