East Coast
The White House Garden Tour, April 21st and 22nd
Georgetown House Tour, April 28th
New York Junior League House Tour, May 5th
Martha's Vineyard Haven House Tour, June 23rd
Nantucket House and Garden Tour, August 8th
Midwest
Minneapolis and St. Paul House Tour, April 28th and 29th
Michigan Heartland Alliance Home and Garden Tour, June 9th
Chicago Modern Home Tour, June 23rd
West Coast
Pasadena Showcase House April 15th-May 13th
Venice Home and Garden Tour, May 5th
Berkeley Heritage Home Tour, May 6th
AIA San Francisco presents Marin Living Home Tour, May 12th
Newport Harbor Home Tour, May 17th
South
Atlanta Peachtree Battle House and Garden Tour, May 3rd
Charleston Upper Peninsula House and Garden Tour, May 5th
(Images: Eric Staudenmaier, Dero Sanford for Fayatteville Modern Home Tour, Claire Bock, Chicago Modern Home Tour, Michael Rex Architects)
Must-See Small Cool Homes: Week Two
Beth's Romantic & Retro Residence
Good Food to Share 
The Big Book of Small, Cool Spaces 
Apartment Therapy Presents 
The Eight-Step Home Cure 
Commercial Flour Sa...
How to Cook Moist & Tender Chicken Breasts Every Time
How To Cook Tender, Chewy Wheat Berries on the Stovetop
The "live" house and garden tours often benefit local nonprofit organizations, making them all the better.
Some others -
MA
http://centersandsquares.com/house-tours-in-massachusetts/
5/17/12: http://www.beaconhillgardenclub.org/tour.html
6/16/12: http://www.southendgardentour.org/
NYC
5/12/12: http://www.thebha.org/
5/20/12: http://www.parkslopeciviccouncil.org/house-tour
6/3/12: www.leffertsmanor.org
http://boerumhillassociation.org/
6/10/12: http://mmpcia.org/site/
http://www.fdconline.org/
Saugerties, NY
http://www.historichousetour.com/
I know it's later in the year, but don't forget the Modern Atlanta Home Tour June 9-10!
http://modern-atlanta.org/ma/get-ready-2012-ma-home-tour/
The 12South Home Tour is in Nashville on April 21. 11am-5pm.
http://www.12southtour.com/Home.html
Hollin Hills, the award-winning mid-century modern neighborhood in Alexandria, VA.is hosting their House & Garden Tour on Saturday, April 28, 2012: http://www.hollinhills.net
The Old North St Louis tour features civil war era through modern day homes in the closest neighborhood to downtown St Louis. Old North has won numerous awards for sustainable urban renewal and is definitely worth a look. This years tour is on May 19th so mark your calendars if you're going to be anywhere near St Louis!
http://onsl.org/house-and-community-tour/
I never miss the Newport Harbor home tour in May. You always get fabulous ideas and inspiration.
I am trying to find out where the house that has wood panelling with the black framing is located. And if you know who the architect is that would be amazing!