A recent study conducted at Northwestern University found that sound can help create a stronger memory. If you play a sound while looking at an image or trying to commit something to memory, then play those sames sounds on loop while you sleep, it can help solidify that memory as it's processed during sleep.
While the study found that this was only modestly effective, it was nonetheless helpful. Next time you need to remember something important, grab your sound effect collection and start making associations.
Sleeping isn't just a time for dreams, but a time when your brain processes things from the previous day. The problem is, you gather so much information during the day that your brain can't process it all and provide you with a perfect memory the next day. However, if you need to remember something, you can help save a particular memory by associating it with a sound. So pick out a "learning" sound, song or album, and give it a try.