Each map is a unique – and very special – snowflake.
We make a lot of maps here in the Fat Pencil Lab. These maps are published in all sorts of different mediums: print, video, web, presentations, white board, dug into sand, etc. And we make maps for all sorts of reasons, highlighting all sorts of different things.
From Google, we have the Styled Maps Wizard: a fairly straight forward GUI that allows you to tailor which geographic features are displayed, what colors to use, and which labels to display. No coding required. Slick.
For OpenStreetMap, cloudmade gives you a head start with many, many user-defined styles. Perhaps one will fit your needs. Or, if not, pick a favorite, hit “Clone Style,” and customize away.