For people that never got to play classic arcade games or just don't want to waste their change, arcade games are now available to play on Wii Virtual Console. Four games are now available; these include Gaplus, Mappy, The Tower of Druaga, and STARFORCE. More information is available on Nintendo of Europe's website.
I must confess, I have never heard of The Tower of Druaga or Star Force. I HAVE, however, heard of Mappy and Gaplus (a.k.a. Galaga 3), although I have never played either.
Some trivia: Star Force, The Tower of Druaga and Gaplus were released in 1984, when arcades were in a decline. Hence, the reason they are not as well known. Gaplus was released in the U.S. as Galaga 3 for name recognition. Mappy was and is more popular in its homeland of Japan. There was a sequel, called Hopping Mappy, that was only released in Japan.