I've heard some of you say that Digg and StumbleUpon can be good ways to market your site. How exactly do you do that? Do you submit your own site to Digg and StumbleUpon or do you have to wait until they find you?
You are allowed to Digg your own site and that's how you do it, yes.
However just make sure that you have a good title and description and make sure that you're not submitting duplicate content. Digg brings in a lot of traffic, but only if your site gets dugg a lot, else you'll receive a handful of visits, which is still better than nothing I guess.
I have had more success with Stumbleupon over Digg and I think that's because StumbleUpon has more specific categories so your content is shown to a more targeted audience. Digg has much more general categories and often times posts that have mass appeal do best (iPods, politics, etc.)... but nevertheless, both can bring a nice stream of traffic if you work them. Every now and then I'll get a flury of traffic from StumbleUpon and it's nice. I also make sure I use the toolbar every now and then and stumble other people's sites. I've found some very useful stuff this way.