Robust, searchable database of publications. Not only can you keep track of all your submissions, but you can also see the stats they've accumulated over time. Choose "Stats" from the top navigation option and select "Publication Response Statistics" to see their top 25 lists: Slowest, Fastest, Challenging, Approachable to help determine where you want to submit. You can also save specific searches for future use. I highly recommend it. https://duotrope.com