The Metal Slug Series メタルスラッグ
The Metal Slug series from SNK is my favourite video game series and Metal Slug 3 is probably my favourite video game of all time (vying for position with JetPac on the ZX Spectrum and the Asteroids arcade version). So whenever I see a Metal Slug arcade cabinet (and they do appear fairly frequently in the independent arcades), I have to have a game or two (despite owning multiple versions on many consoles at home).
The first game in the series came out on April 19th 1996 on the NeoGeo MVS, and has subsequently been released on the NeoGeo CD, NeoGeo Pocket Colour, Sega Saturn, Playstation 2, PSP, Wii, PC (Steam) and mobile platforms.
There have been seven iterations in the Metal Slug series, the last being a Nintendo DS, PSP and Xbox Live Arcade release in 2008~2010 (depending on the platform).
More information on the Metal Slug series can be found on Wikipedia (where else!).