Quine that takes as input the name of a language and outputs the same thing implemented in the input language From Quine central:

Write a quine that takes as input the name of a language and outputs the same thing implemented in the input language.

The source article has something you can work from, but as the author says this is much harder. Obviously you only need to support a limited set of languages. The choice is yours though, as well as the base language.

As a code-challenge, your score will be the number of languages your program supports; higher is better.
Ruby

require 'json';s=%q[{"ruby":[" %q[","require 'json';s=##;j=JSON.load s;puts j[l=gets.chomp][1].sub('##',j[l][0].delete(' ')+s+j[l][2].delete(' '))"," ]"],"python":["' ''","import json,re;s=##;j=json.loads(s);l=raw_input();print(re.sub('##',j[l][0].replace(' ','')+s+j[l][2].replace(' ',''),j[l][1],1))","' ''"]}];j=JSON.load s;puts j[l=gets.chomp][1].sub('##',j[l][0].delete(' ')+s+j[l][2].delete(' '))


Python

import json,re;s='''{"ruby":[" %q[","require 'json';s=##;j=JSON.load s;puts j[l=gets.chomp][1].sub('##',j[l][0].delete(' ')+s+j[l][2].delete(' '))"," ]"],"python":["' ''","import json,re;s=##;j=json.loads(s);l=raw_input();print(re.sub('##',j[l][0].replace(' ','')+s+j[l][2].replace(' ',''),j[l][1],1))","' ''"]}''';j=json.loads(s);l=raw_input();print(re.sub('##',j[l][0].replace(' ','')+s+j[l][2].replace(' ',''),j[l][1],1))


Both versions take input on stdin (ruby or python currently) and generate the output to stdout in either language.