Look at this link
it has over 20+ usefull DIY projects
a few of them i want to try hahaha
http://www.aquariumlife.net/diy.asp
DIY AIRSTONE PROJECTS
DIY Airstone Manifold
Quick and Cheap Do It Yourself Airstone
DIY AQUARIUM - OTHER
A Primer on General Aquarium Design
Make Your Aquarium an Endless Aquarium
Simple DIY Brine Shrimp Hatchery
DIY AQUARIUM CHEMISTRY
DIY Yeast Generated CO2 Injector
DIY AQUARIUM STAND PROJECTS
Building an Aquarium Cabinet
How to Build a DIY Aquarium Stand
DIY AQUARIUM TOOLS PROJECTS
Build a Better Fish Trap
DIY Tool to Drain, Fill and Clean Gravel (Similar to Python)
How to Build a Simple DIY Fish Trap
DIY DECORATION PROJECTS
Aquascaping an African Cichlid Aquarium
Cave Grotto Aquarium Background
How to Make a Weighted Anchor for Plastic Aquarium Plants
Low Cost Aquarium Substrate
Make Your Own Background From Styrofoam
Make Your Own DIY Aquarium Cave From PVC Pipe
Quick and Beautiful DIY Fish Cave Made From a Coconut!
DIY FILTER PROJECTS
DIY Protein Skimmer from PVC
DIY Trickle Filter Made from Home Depot Buckets
Make Your Own Fluidized Bed Filter
Make Your Own Sponge Filter
Quick and Easy Wet/Dry Filter
DIY FISH FOOD PROJECTS
DIY Frozen Fish Food
How to Hatch Brine Shrimp
DIY LIGHTING PROJECTS
DIY Compact Fluorescent Lighting For Less Than 20 Bucks!
ODNO Lighting
DIY OVERFLOW PROJECTS
Compact Standpipe Design for Hang-on Overflow Boxes
DIY - Skimmerless Overflow
DIY Overflow Box
DIY Overflow Using Only PVC Pipe
Overflow for Wet/Dry Filter or Sump