I'm gonna play it safe and go with guys I'd imagine to be widly availalbe...
Glen Perkins (though he has had a hot start, so maybe not)- He pitches to contact, not a strong strikeout guy, but he pounds the strike zone, so his walk totals should be low and his WHIP likely low as well.
Dave Bush- Notorious for a low WHIP and an ERA that doesn't match. Not a big fan, but if you are looking for someone to exclusively help WHIP, he is likely capable.
Tim Wakefield- The knuckleballers career WHIP is 1.34, and was 1.18 last year, decent bet for solid WHIP on a healthy number of innings pitched.
Koji Uehera- Big time strike thrower according to everything I've read, his stats in Japan, and his stats thus far. There might be a bit of upside here too... but not a ton.
Rick Porcello- He'll have his bumps and bruises, but he's not issuing many free passes, and he's pounding the strike zone. His groundballing ways should net him some double plays in the event he does give up some base hits here and there, therefore limiting the damage.
Hope those names are of some assistance.