I'm using Digg to build backlinks,but i find my digg disapear soon after i digg.Too many others push my digg down. How can i do?
You probably need to network with some Digg users and make some friends their, specially those who have common interest as yours. This could help your diggs, and also add Digg button to your posts ... goodluck!
Until and unless you get more than 56 diggs for your post, your will not be promoted to home page of digg. Therefore to promote your post on digg you need to have many friends who can digg your posts within a day.
To get traffic or digg from digg, you need to make more friends in digg. It is all about speed, you need to have more friends in digg to help you digg so that your article can stay at the homepage, then you will get traffic
I agree, Digg is useful for getting your site indexed. It can rank quite high for long tail keywords (in my experience)