Well, here is the Infamous "there's one on every website" Link Page.  I only have a few links here, but I will add more in the near future... as soon as I get all of my notes organized, that is!  Have fun surfin'!

DIY (Do It Yourself)

The Caretaker at OZ REEF Marine Park - At last count, he has 237 different DIY plans!
http://ozreef.home.ml.org/diy/index.html
DIY WaveMaker
Schematic of a WaveMaker
Eastern PA Reef Club - follow links to the DIY section!
Protein Skimmer Plans - on Charles Delbeek's WebSite
Water Top-Off System - on Charles Delbeek's WebSite

UseNet NewsGroups

Mailing Lists / LISTSERV

ReefKeepers e-mail list Archive

Lighting

Hamilton Technology - Metal Halide (MH) bulb manufacturer
PFO Lighting, Inc. - Metal Halide (MH),  High Pressure Sodium (HPS), Retrofits, Hardware
Aquatic Lighting Systems (ALS) - Metal Halide (MH) Retrofits
Coastal Growers - Water cooled Metal Halides (MH)
General Electric (GE) - Metal Halide (MH) lamps

Filtration

LifeReef Filter Systems
Custom Aquatic Life Systems
Hanna InstrumentsLifeReef Filter Systems
Custom Aquatic Life Systems
Hanna Instruments
AquaCare - European Distributor of Water Treatment, Filter Media and Monitoring/Dosing Devices

Instrumentation / Measuring Devices / Sensors

Hanna Instruments - manufacturer of electro-analytical instrumentation

FAQs (Frequently Asked Questions)

Reefkeeping FAQ - HTML "clickable" version
reefs.org ReefKeeping FAQ - a "work in progress"
ReefKeeping FAQ Part 1 or ReefKeeping FAQ Part 1
ReefKeeping FAQ Part 2 or ReefKeeping FAQ Part 2
ReefKeeping FAQ Part 3 or ReefKeeping FAQ Part 3
Aquaria NewsGroup FAQs

Personal Home Pages

Charles Delbeek's Homepage - Co-Author of "The Reef Aquarium"
Sanjay's Reef Aqaurium Pages
John Rice Reef Page - nice site.   Great info on Mangroves!
John Newton's Slice 'O Reef
The Coral Frag Trading Post  - Paul Auger Jr's Coral Page
Richard Durso's 180g Reef Tank
The Marine Aquarium  
Coral Reef Fishes  - Luiz A. Rocha's site
The Reef Ring  - WebRing of Personal Pages dedicated to ReefKeeping!
The Acropora Connection  - Brian Kubicki's Acropora Page
Reef Addiction - Rick Martin's Addiction!
Reef Chat  
Keith Clarke's Reef Page - with a DIY MH Pendant and Tropicorium Trip Pics!
Jason Lile's Homepage
Alok's Fish Page
Home Page of Daniel Maughmer
Simplified Reef Keeping - Robert Metelsky's website - author of Simplified Reef Keeping
John T. Croteau's Home Page
James Fox's Home Page
Brian Ferguson's Home Page
Doug's Home Page
Minnesota Reef
William Wasserman's Home Page
Nathan Cope's Mini Reef Aquarium Pages
Keith and Lisa's House
Jon's Simmons Reef
SPS Coral Homepage
Eastern Pennsylvania Reef Club
Jim Power's Reef Page
Norm D'Allura's Reef Tank

Online / Mail Order / Wholesale Aquaria Supplies

Maine Coast Sea Vegetables - Fresh Sea Weed for your Tangs and other herbivores!
Flying Fish Express 
Pet Warehouse
Jeff's Exotic Fish
Quality Marine USA
Aquatic Warehouse
Reef Science International  
Something Fishy - The Marine Aquarium Home Page  
Reefers Marine Aquaria Store
Premium Aquatics
Scientific Corals
Coral Farms
Marine Ecosystems - Aquarium Maintenance Service in Greensboro, NC  USA - also has an online store!
Indo Pacific SeaFarms
Thiel Aqua Tech
Tampa Bay Saltwater - Florida's Live Rock Farmers
Aquaculture Supply - downloadable catalog in .pdf format
Inland Aquatics - catalog and discussion lists
Sylvania Tropical - LFS near Toledo, Ohio USA

Online Magazines

Aquarium World Magazine
Aquarium Frontiers Magazine
Aquarium Net Online - another good reference site!
Thiel Technologies - 4 searchable saltwater libraries!  Great reference!

Fish Breeding / Info

Angelfish Breeding: Frequently Asked Questions
The Breeder's Registry

Non-Profit / Reference Sites / Clubs & Organizations

Fish Information Service (FINS) Index
Aquaria Central
Western Marine Conference - April 16th, 17th and 18th, 1999 - Vancouver, BC, Canada
Reefs.org
Eastern PA Reef Club

Freshwater

Luky's Aquarium Page

Sea Horse Info

Seahorse Research Society

Artemia / Brine Shrimp / Algae

Artemia Culture FAQ 2.0
Brine Shrimp Direct - Source for Artemia Cysts and Brine Shrimp Egg products
Rotifers.com - Utah based, live critters for feeding, sandbeds or refugiums
Carolina Biological Supply  1-800-334-5551

Anemone Info

Host Anemones