This is a simple little trick that can get you some free space out of your memory stick. I'm pretty sure most of you have used your memory stick until it shows up as KB instead of MB on your PSP, well I have found a way to get a little more KB out of your memory stick.
Step 1: Connect PSP to Computer
Step 2: Press Start then Search
Step 3: Select "All files and folders"
Step 4: Put *.db in "All or part of the file name"
Step 5: Set "Look In" to your PSP's Drive Letter
Step 6: Press "Search"
Step 7: Remove all items that show up.
There you go! Now you have a little more space on your Memory Stick. I went from 3426kb to 3680kb!
I am not responsible for any damage caused to your PSP or Computer if you try this. Do this at YOUR own Risk!