The possibilities are endless for a custom DIY rethemed pin.
It just really depends on your own personal taste.

Cartoon or comic book characters are a great choice if you are looking for a friendly/family themed machine.
Anime could be cool with or without the tentacles.
Old favorite TV shows from your childhood.
Your favorite movie.
Zombies like a number of people have already mentioned.
A generic halloween or haunted house theme, ghost and ghouls.
Your favorite band or singer.
Your favorite muscle car.
Super models.
Greek Mythology.
Sci-fi or horror.

Here is a list of custom pins I have found while surfing the web, enjoy.

Astroboy - created from Magic pinball machine
http://users.chariot.net.au/~barky011/Astroboy.html

Hellacopters - created from an King Pin pinball machine
http://www.pinsane.com/pinorama/machines/HELLACOPTERS/qt/index.shtml

AC/DC - it is listed in a forum
http://archive.maaca.org/s107351202.onlinehome.us/cgi-bin/Blah/Blah.pl?m-1146309506/s-all/

Battlestar Galactic - created from an Evel Knievel Pin
http://home.insightbb.com/%7Egalactica53/BG_Pinball/bgpinball.htm

Three Stooges - created from a Dolly Parton Pin
http://webpages.charter.net/strange218/pinball_website_007.htm

Coconut Island - custom built from scratch
http://www.users.on.net/~spaners/Coconut%20Island/index.html

Gooligan's Hooligans
http://1930s.com/pnv/gh2006/index.html

South Park - before the official one was released
http://www.pinballreviews.com/southparkcustom.htm

Egg World
http://www.floweringnose.com/i_pinball.htm

Capitol Pinball - custom built
http://www.kendallvanpool.com/Caploungepinball/index.htm

MARS ATTACKS - created from an old Password Pin
http://home.comcast.net/~josh.kaplan1/mars.htm

Cosmic Colony - created from a Space Shuttle pin
http://pinmolder.com/cosmic_colony_pinball.htm

Gothic - custom built
http://www.phobe.com/pinfools/index.html

Porsche Boxster -
http://users.telenet.be/mushroomamusements/projects/projects.htm

Comet Commander -
http://www.ece.umd.edu/pinball

Critical Mass -
http://www.theyorkshow.com/cm.html

A Slovenian art project, custom pinball
http://www.aksioma.org/machinazois/photos.htm

Quoted from bowman9

...AC/DC - it is listed in a forum
http://archive.maaca.org/s107351202.onlinehome.us/cgi-bin/Blah/Blah.pl?m-1146309506/s-all/

... that is here by the way... the s107blablabla page is the generic server name for http://www.maaca.org.

x men or scooby doo

Although doing a conversion would be rewarding enough, it might be a good idea to have a buyer lined up, perhaps even doing a conversion of their own choosing ( within limits of course ).  The fact that you are being paid for the 100s of hours you will spend on the machine ( albeit, probably less than minimuim wage ! ) would get you through those rough patches where you just want to torch the thing cuz it's not working out.  

Quoted from mrniceguy

Although doing a conversion would be rewarding enough, it might be a good idea to have a buyer lined up, perhaps even doing a conversion of their own choosing ( within limits of course ).  The fact that you are being paid for the 100s of hours you will spend on the machine ( albeit, probably less than minimuim wage ! ) would get you through those rough patches where you just want to torch the thing cuz it's not working out.  

I dissagree. Do it for yourself... you end up more motivated then. If you do it for someone else, be ready to deal with a lot of pressure.

Quoted from Sparky

I dissagree. Do it for yourself... you end up more motivated then. If you do it for someone else, be ready to deal with a lot of pressure.

I live for pressure !  Oh wait, I got it wrong.  I live for pizza.  Yeah, I hate pressure.  

Although it has been mentioned in a past thread I would like to see a "The Munsters" pin, done right and in color.  Addams Family was released in 1993 and I think there's room for another pin with this type of theme.


http://www.youtube.com/watch?v=oFCnvH2E-6A

http://www.youtube.com/watch?v=DE1AviS5mAg

                                                                                   flashman

  

Quoted from jonny_eh

A zombie theme would rock. I'm really surprised no one ever made a zombie themed pin before. It would even fit on an EM, considering zombie movies have been around since the 60s.

I ' m not a Michael Jackson fan , far from it , but i like the idea of a zombie theme . So , "THRILLER" in EM ...

What about a homemade "MAACA" machine. It could have artwork that included pic of a person helping another, a pic of a lowballer with horns,a couple of handshake pics, pics of guys almost busting there guts lifting stuff, pic of a guy trying to stuff 5 pins in a volkswagen rabbit( on the roof and the hood as well) a couple of broken beer bottles incorporated into the playfield, pic's of people tearing their hair out, and maybe even about to take a sledge to a machine, and why not an artists rendition of the auctioneer from starburst as well. The soundtrack could play ac/dc ' s shoot to thrill.

powerslave and I both vote for an Iron Maiden pin...

err... wait... not that one... the band!

Quoted from sentinelking

powerslave and I both vote for an Iron Maiden pin...

err... wait... not that one... the band!

Already been done.

This would be a kick @ss back glass for a halloween themed pin.

http://imagecache2.allposters.com/images/adc/10100919A.jpg

http://www.allposters.com/gall.....8_09_01_archive.html