Quick feedback:
* I like the idea. Reminds me of Google's CSE tools, but with individual crawling control.
* I think you need to proofread the text on the main page a bit. Some of it doesn't parse correctly for me, for example: "You decide what sites to crawl indexed and search"
* A lot of your links on the right are 404 or missing.
* Your signup form does not accept emails with a "+" in them. So I cannot signup with my default email address. Please resolve this if you can.
* So the crawler itself has to be a local app? In other words, my local computer is doing the crawling? I had assumed the service was that your site would do the crawling based on the information I provided and on the schedule I wanted.
Seems like an interesting project, but you do need to work on the user-facing aspects a little to prevent people from being confused.
The layout is pretty unprofessional, so it doesn't encourage me to want to download an EXE client to run locally.