Record Clamp
Record clamps help level and stabilize records on the turntable platter. They usually run $25 and up. This instructable shows how to make one for a dollar.
Obtain a Hockey Puck
Pick up a hockey puck with standard weight.
Find the Center
Use a caliper and compass to find the center of the puck. Mark the spot.
Drill
Drill the center through with a small drill bit and redrill the hole with larger bits until the hole accommodates the spindle on your turntable.
Set on Record
At this point you could add metal to the puck to increase weight, but I find the compression sufficient. You could also paint the puck or add a bullseye level to the center for a few dollar.
Play a Record
Place the record weight on a record and give it a spin.