I would never copy and paste an article or Hub to another site. (and I wouldn't just tweak it a bit either) However, there are sites where you can submit a link to your Hub and write a short unique blurb about it. You don't have to re-write the same thing, you just provide a summary or a teaser.
Xomba for instance lets you submit "bookmarks" where you just write a teaser paragraph and submit your Hub. (it's a no follow link but you get AdSense revenue.
Snipsly is another example (they allow you to include several links; Do Follow at that, and provide Adsense Revenue sharing.
A new favorite of mine is Best Reviewer. You can submit several of your Hubs at once. You write a paragraph to introduce your topic, then list 3, 4, 5, 6 or more items (each of these items are links to your Hubs. It's like writing a Top 5 or Top 10 list. (Like "The Top 10 Things to do in Singapore" or "The Top 5 Work at Home Jobs") It takes minutes but you get several Do Follow backlinks as well as AdSense Revenue sharing. (if you decide to try Best Reviewer it would be "nice" if you contacted me and I could send you the link to visit the site...you get AdSense revenue sharing for people you refer)