I tried...
to look into that nagging question of who's putting money into Nader's campaign, but no luck. The tangle of those new 527 committees seems impenetrable (by design, of course). The usual sources for campaign financing records just show who donates to the committees, but there's little info on who they're spending the money to support; and the "issue advocacy" dodge helps obscure exactly who's supposed to benefit by particular ads and other campaign spending.
On the surface Nader's campaign is a pauper, and Ralph himself is the biggest donor, at a paltry $40K. Of course, somebody who wants to covertly fund Nader to spoil Kerry's campaign isn't about to donate directly to the campaign; the PACs and 527s exist to launder the money.