livingsocial has this voucher for $10 for a 60- to 90-minute tour of the groundbreaking Farnsworth House in Plano (a $20 value).  Situated on a private 62-acre estate, the streamlined steel and glass structure was built in 1951 and is one of the most famous examples of modernist domestic architecture.  The last time they offered this deal was in August of 2011, so if you’re looking for staycation ideas, grab it now.