HNsearch.com, Topsy.com, pinboard.com, stackoverflow.com, getprismatic.com, subreddits for specific topics.
Sometimes, delicious.com, which i used to go every day.
subject matter specialists on twitter,
If i'm not researching something:
I open chrome and firefox pages to manage extensiosn/addons and those are the only pages i let myself open (my version of no-procrast)