Soak 'em in soda water for a couple of minutes, then circular rub from the inside out with a very soft cloth.

Or you could lick 'em. I hear llama spit has disinfectant qualities.

actually just starting out with water and a clean cotton rag works most of the time (for fingerprints, etc.) Clean cotton rags do not (generally) include the tail of your tee shirt, in case you were wondering.

Don't run the cloth in circles around the disk. Work the cloth back and forth between the edge and the center working around the disk. (This is what Uncle Pinky said, I'm just naturally verbose.)

For more than fingerprints, there are other options - soda water being one. DO NOT use any type of solvent. I'm not sure I would even try white vinegar. Cloud the plastic and the disk is toast. Window cleaner, will cloud the disk for example. Same is true for some moist wipes.

For scratches you can have them polished (or buy a polisher) This is a last resort because it does remove a tiny layer from the disk.

The SkipDR from Digital Innovations

http://www.digitalinnovations.com/products.php?cat=1

Put them in the dishwasher on "rinse" with cold water.

No. No. No.

The dishwasher needs to be set on "pots & pans" or else you won't get all the little scratches out of the DVD's.

Every time I get a disc from Netflix I wipe the entire disc from the inside to the outside with a bounty paper towel wet with rubbing alcohol. The rubbing alcohol tends to dry a lot faster than water.

Gets rid of finger prints and any most foreign matter like dirt or sticky stuff (which I'm hoping is just soda or something).

With serious scratches it's hit or miss. And sometimes a scratched DVD won't play in some players but work perfectly fine in others.

Found "The Spongebob Squarepants Movie" under a carpet in the living room once. Fuggedaboutit.