Traveling Spoon "a platform that connects people with authentic food experiences (think in-home meals, cooking classes, and sometimes market tours) by locals in their own homes"

Over Long Distances:
Get Going (choose two destinations; the site picks one for you; good discounts)
kayak for buses (busjunction) (sometimes partially broken)
Travel Zoo
Flyer Talk (discussing deals)?

Seat Guru, Seat Expert

Flight On-Time Statistics

Routes of Low-Cost Airlines (NYT)
Rick Steve's List of Low-Cost European Airlines Sites
WikiTravel's List of/Info on Discount European Airlines

Airplane Ticket Price Forecast
Historical Airplane Pricing Data
Air Fare Watchdog (from SFO/OAK/SJC)

Yapta - automatically ask for air ticket refunds

Winery Maps; Maricia recommends Cosentino

Travel Guides:
Lonely Planet
Eyewitness guides (DK Publishing)
Travel Blogs
Travel Wiki
Economist City Guides
Yahoo Travel Guides
NYT Travel Guides (36 hours in North America guides; Affordable Europe guides)

Where To Go:
Monthly Weather Averages
Sunrise and Sunset Times

Bidding Strategies for Priceline
One-Month in Advance
Trip Advisor (maps)

Furnished Apartments:
Slow Travel (reviews and listings)
Vacation Rentals by Owner, rentalo, flipkey
also, zonder,
Vacation Rentals Watchdog
Airbnb, or maybe crashpadder or iStopOver or interhome

Funky Places to Stay:
Odd Inns (and treehouses and lighthouses and boats and more)
Treehouses in Southern Oregon (rec by John D.)
see bookmarks on flipkey