If there’s a cooler do-it-yourself site than Instructables, I haven’t found it. The place is home to thousands of fun, wacky, practical, money-saving, scientific, and innovative projects authored and illustrated by your fellow humans.
During these hot summer months, I’m working my way through the site’s Outdoors section, which includes such nifty projects as the KidWash PVC Sprinkler Water Toy. (Hardware stores must absolutely love Instructables.)
The site is free, of course, but it’s worth registering (also free) so you can view/print any given project’s instructions on a single page rather than having to jump from one page to the next.
If you’re interested in other how-to sites, check out WikiHow, another favorite of mine. In the meantime, if you’ve built/created/hacked anything particularly cool using an Instructables project, tell me about it in the comments!