I like Dave Barry's suggestion from a column he wrote back when the show first premiered: "You have the 50/50, Ask the audience, or you can have me shout out the correct answer, like this: 'IT'S D, YOU MORON!'"
In all seriousness, I'd advocate a return of the 'Switch the Question' lifeline, but with a twist. The contestant gives the show what s/he thinks are their three best categories before the show, and when s/he chooses to change the question, it's swapped out with a question from one of these areas. Call it 'Hey, remember that Wink Martindale show 'Debt?' That was pretty cool.' Or maybe just Switch the Question again.