If by 'public' you mean 'public, but in a way that ensures the information is not particularly useful'.

http://en.wikipedia.org/wiki/Political_action_committee

Have fun following the paper trail when donation disclosure can be delayed, and you can accept donations to your committee from other committees, creating as long and obfuscated a donation trail as you like, and then take the pooled-together corruption money and use it for anything you want.

I suppose it is still better than secret compensation under the table for favors, though. In some sense.

Government is one way to ensure criminals (politicians) report (some of) their earnings.