What I've learned from CSS3 Logos is that having fun is the key to succes.
Why create something useless?
Well, they aren't actually useless! When I've started creating the patterns I've told myself: enjoy what you do and create things that might be useless if that's what it takes to make something beautiful.
Easy to adapt
If you visit the page for each pattern you'll see that they are incredibly easy to scale! But what if you want to change the colours? Just do a simple find-and-replace for 2-3 solid colors. 30 seconds tops!
Learning is fun
Another thing is that while creating some complex looking patterns I had to learn a lot about CSS3 and I've used some cool new stuff that I think will hellp you start learning CSS3.