During LMC we spent some time on Toonbooks which complement our physical copies of the same titles. I have added a link directly to Toonbooks on Links 4 Kids so it is accessible from any netbook. You can search Google for "Schenk Links 4 Kids" or use this shortened link http://is.gd/scharks.
Another site that I have added to Links 4 Kids is Literactive. This site has some great content for early readers. Some time back I created a general account with username schenk and password schenk. This will allow you access to the whole site. One nice feature of Literactive is a contained environment for sequential, at your own pace, literacy activities. It is ideal for a literacy center activity.