Protecting the surface of your board games...
The usual recommendation is to get a sheet of plexiglass (known as Perspex&reg; in the UK) and lay that across the board when you're playing.  It's an especially good solution for "board" games that don't actually have a board.

Well-made board-backed games don't really need any help, but many small-press games have the board printed on stiff card or even paper.  Paper gaming surfaces go back at least to SPI's foundation in 1969, and so do plexiglass coverings to prevent them getting ruined.