I would love this idea, if it was limited to 10-20 lines. The forced conciseness of it would make devs focus on brief concepts and structure, rather than complex methods. It would end up being like Dribble rather than Gist/PasteBin, and be a great place to browse for techniques I hadn't previously encountered. Think about how fun it would be to scan through an Instagram style list of stuff like this:

############~C~#############

  if ((1?1:var)/2) {
      /* it's floating point */
  } else {
      /* it's an integer */
  }

#######~Objective-C~########

  + (NSString *) append:(id) first, ...
  {
      NSString * result = @"";
      id eachArg;
      va_list alist;

      if(first)
      {
          result = [result stringByAppendingString:first];
          va_start(alist, first);
          while (eachArg = va_arg(alist, id)) 
              result = [result stringByAppendingString:eachArg];
          va_end(alist);
      }

      return result;
  }

#########~PHP~##############

  $object = new StdClass;
  $object->foo = 'bar';
  echo json_encode($object);

############################

I know they aren't the best example, but I would love to be able to scan through a list of small code snippets (by language) that demonstrate concepts. On the plus side, it would be an easier way to show some competence in a language (for future employers) than having to do massive contributions to open source projects (don't have that much free time). The thing that makes or breaks this project is a smallish limit on lines. Without it, you are just another Gist/Pastebin, without the benefits of the wide user base and additional features. I have zero desire to chill at night and scan through a bunch of random 100+ line snippets that I have no context for, but I love goofing around on Stackoverflow, looking at fancy code snippets