There's two levels of cleaning old vinyl discs. The first is the habitual light dusting done before every play. The second is a serious bath to rid the grimesters. Let's talk about that, shall we?
Like washing your car, there's the manual and automatic washes available. Rich, dedicated hepsters can buy machines like the Loricraft, the Nitty Gritty (I want one of these), or do-it-yourselfers can build one at home.
Most of us, however, clean manually. Here's a beautiful article on cleaning. Great text and photos.
Here's another good overview of record cleaning, lots of ideas here.
Cleaning fluids are expensive. Here's a link on several record cleaning formulas.