Some sewing machine geeks like to have one. It was Singer's first zig-zag machine, as I understand it. Those keys on the end are used to change the pattern. The black ones are more desirable than the green ones.
They do take a non-standard needle, but they aren't hard to find or particularly expensive. They are available on ebay and on some sewing machine parts sites.
I decided that I wasn't a good enough geek to deal with something that complicated, so I passed mine on.
They machines don't bring very much money, either.
bkay