There's a certain joy that comes from building an extraordinary thing out of ordinary pieces.
Anyone who ever has chained together command line applications into a workflow will know this special kind of joy.
There are a lot of patterns from 15+ years ago that I wish people would rediscover the joy of:
Yahoo Pipes
Folksonomies
RSS
Composable, single-purpose command line applications
Anything Clay Shirky ever thought was cool :-D