Do sites such as digg allow you to submit articles from your site. Or will they catch you out if you do too many from the same site?
Most of my articles and news are Digg-worthy. As long as it is original, and in no way has Digg-seeking intentions (and is something people will care about), then they have absolutely no problem with webmasters creating Diggs for their own sites (I've talked to their support personally about this issue). However, never create fake accounts or try to somehow boost your Digg count for a Digg you made. Though it may work one or two times, you'll be caught, fast.
Digg has things in place to detect spam by itself, and also if enough people see it, admins can ban you. Tons of sites have been banned from digg simply for insulting it.