Thanks to an anon e-mail, here we go:
2008 candidate Tyler Banham in Hamilton Mountain. (Declared)
Former MPP and provincial cabinet minister Marie Bountrogianni in Hamilton Mountain (rumoured)
Bob Bratina, a popular city councillor and radio host in Hamilton Centre (rumoured)
2004 candidate Debbie Zimmerman in Niagara West—Glanbrook (declared)
Kitchener mayor Carl Zehr in Kitchener—Conestoga (rumoured)
2008 candidate Jacquie Gauthier in London-Fanshawe (declared)
I've also heard that Larry Di Ianna in Hamilton East-Stoney Creek and Dan MacLean in Ancaster-Dundas-Flamborough-Westdale will almost certainly be the candidates in their respective ridings.