Evidence of Other Crimes, For What Purpose?

I read today Judge Biggers is going to allow evidence of other crimes. This is the the Wilson v. Scruggs, Judge Bobby DeLaughter, Trent Lott, Joey Langston, Tim Balducci, Ed Peters, Steve Paterson stuff. Evidence for what purpose? Can you really use "evdence of other crimes" to prove the pre-isposition necessary for the government to say there was no entrapment? Seems a stretch. And, then, whose pre-disposition is being established -- the pre-disposition of someone who is not a party to the acceptance of the judge's offered bribe. My head is spinning. It does not seem "other crime evidence" can be used to establish pre-disposition.