TeXample.net has been a great gallery and resource of TikZ examples, curated by Stefan Kottwitz. Graph plots were included on TeXample.net, but as the pgfplots packages became more flexible and feature-rich, Stefan has decided to dedicate a separate gallery to it — and thus was PGFPlots.net born!

The graph plot examples are already looking delicious, so head on over and take a look. Do share your own examples as well!