One really horrible usability point: when I enter a custom pattern on the right, I can't click enter to submit the form, but instead I have to go across the screen, up, and click the small Go button. Either do it live with AJAX or just add a proper form to refresh the page.
And I'll point out that it's spelled "scarce". It's not obvious what that column means even without having to decipher bad spelling.
To build on that: having the form split up is a bad idea. The sidebar serves no purpose really and I recommend all the form functions be collected at the top and bottom of the results.
I'd also rename the Go button to something more sensible like "Search" or "Find". Go has very few good use cases, and even then it's dubious.
I really like this idea. I spent several minutes looking through the suggestions and bookmarked it for later.