Microgames are a kind of game that has been around for a while but seem to have gained in popularity lately. These are board, card or war games that fit in a very small package. Examples of these include: Button Men and Pennywise from Cheapass Games and Kickstarters like the amazingly successful Coinage.
These games seem to fill an interesting niche in gaming. Usually they are short, quick games that can be played in under half an hour with very little setup time. They make a neat palate cleanser between larger games. It is also possible to get in a couple of games in a few minutes or over a lunch.