Your robots.txt doesn't contain anything. Submit your site to other search engines, social bookmark, and build some good links and you'll get indexed eventually.
This is not any solution to submit your link in digg. I have done this job and still doing so if you are really interested in solving this issue then you should PM me with your site URL.
According to your done methods, it should be indexed in google. Maybe your website including some unhealthy things the google search engine think, and or if you link exchange with other websties, and others's websites are punished by google, which lead to your website embroil.
May be the links which you have build are from NOFOLLOW or your robots.txt is blocking google index if you have copied from other place than check it.