Digg, Twitter & Social Bookmarking

I'm no Twitter ninja but here is what some of those who are recommend:
A minimum of 2 tweets per day, e.g. one in the am and one in the pm.
One tweet with a link to your site or a site promoting your site.
One tweet to another article, blog post, news story, etc. related to your market.
Don't worry about anchor text, concentrate on building a following.
I would do the above for each site I wanted to promote.
I wouldn't necessarily create a separate account for each site if the sites are in the same niche.
If they are in totally unrelated niches then I would.

Somebody else will have to chime in on Digg as I don't spend any effort there.

As for profile links, use your anchor text.
The fewer links you use, the less spammy it will appear.
Reality is that most profile links may be deleted regardless.
Since you only have one content page, you'll need to point your anchor text links to that page. The more pages you add, the more pages you can backlink to and the more keywords you can work into your content. Plus with enough pages, you can develop an authority site which will get more SE luv.

Try and get your twitter account with followers that are related to your niche site. 1 account per website you have and want to promote unless same niche. Follow 50 people a day. When you have a decent following promote your site via your quality content posts you make to get them back to your site. The better the content is the more the people will come back and tell there friends.

Facebook fan pages work the same way. Digg i have no idea about.

Hey dude

Just found this article:

TOP TIPS ONLINE | MARKETING,ADVERTISING, SEO, MAKING MONEY: How to get dofollow backlinks from social bookmarks?

Hope it helps :p