Its a tricky topic, not encouraged but it could get you loads of traffic or it could get your site banned from Digg and possibly major search engines

Yeah i would agree, dont do it hey, it is not worth it in the long run and good point about the banning, It think John Chow got accused of this by Digg? and had his site baned.. Your better off focusing on unique content, thats what brings traffic, and is ethical for generating traffic..
Your better off joining heaps of interlinking social networks like digg and making friends and then asking them whenever you submit a new dig ask them to consider digging it..

I have never tried that one. I still prefer to be voted naturally without the need of paying other people to vote my posts on digg..