I'd Also Like A Pony
a) be seen as relevant
b) distance himself from the Liberals
depending on how the Grits react. The conventional wisdom is that the Liberals want to wait as long as possible for a vote in order to put some distance between election and the Gomery report. I'm sure they'd also love to see Ralph deliver a pre-election budget full of goodies. We also know that Harper doesn't want to bring down the government without NDP support, for fear of looking like he's an election crazed separtist co-conspirator. Add it all up and Layton should continue to be the centre of attention.
As for his list of demands, it appears he's kept them vague enough so that he can say the Liberals either accepted them or rejected them no matter what they do. Once again, likely a smart move.