Shopping:
Ebay | Craigslist

Deals:
Dealighted | RetailMeNot | Gas Buddy | Cheapism

Music:
Piano Street (sheet music)

TV/Movies:
Just Watch | NBA Streams

Reference:
instructables | How To Clean Stuff

Academic:
YouTube EDU | Academic Earth | Einztein (college online videos) | Khan Academy | Personal MBA

Food stuff:
PunchFork | OpenMenu | Eat The Seasons | OpenTable

Travel stuff:
101 Holidays | Take the Family | Flightfox (for multi-city or international) | AllTrails | Best Parking | Bidding for travel | BetterBidding Bidding Traveler Priceline | Travelocity | Farecast | ITA Matrix (First Class search) | Hipmunk | routehappy (Search with amenities, class) | Kayak | Vayama (International Flights) | Seat Expert | Cheap Tickets | Car Rental Codes | Airport Parking | iStopOver | Best Fares | Expedia | Hotwire

Programming stuff:
Code | Scratch | Stanford CS Library | Joel's recommended programming books | Stack Overflow | STL | Pragmatic Programmers | GNU make | GDB | Code Guru | Thinking in Java | Andover.net

PHP:
PHP.net | Practical PHP Programming | Extension Tutorial

Python:
Official Python Site | Byte of Python | Dive Into Python | Thinking in Python | Python Cheatsheet

Languages:
FSI Language Courses

Finances:
Index Funds | Stock Option Advisors

Music:
Church Sound Check | American Music Supply | Harmony Central | Ampage | Amptone.com | Musictoyz | Professional Audio | Zzounds.com | Gryphon Strings | Wildwood Guitars

Christian sites:
Cumberland Valley Bible Bookstore | Worship Together

Guitar chords:
Christian Guitar Resources | Christian Guitar Network | Rockin' with the Cross | Christian Guitar Tab | Chord Find

Audio/Video:
Monoprice (A/V gear) | Digital Bits | Home Theater Magazine

Movies / TV:
Hollywood Jesus | Drew's Script-O-Rama

Random:
For me Dave and Henry | Bellarmine College Preparatory | Dialectizer | How Stuff Works |

Health sites:
National Institutes of Health | Centers fo Disease Control | National Committee for Quality Assurance | Merck Manual | American Heart Association | American Cancer Society | American Diabetes Association | American Academy of Pediatrics | Mayo Clinic | Medline | National Library of Medicine | FDA