It's very easy to find author information online--use their personal site, their publisher's site, their Amazon bio, etc.
Another awesome advantage of online searching for authors is if their interviews are available free digitally. Again, fairly easy to search (author name inside quotes and the word "interview").
One of the coolest ways online sources can help you is scanned or re-typed primary sources.
(scan of actual Luttrell Psalter)
Other helpful online sources will be professors' informative sites, museums, historical society pages, sites dedicated to quality information (not sites like about.com or infoplease), and things like that.