Learn Click is a site that can help you with that. In a matter of minutes you can add some text (copy and paste) and then choose the words that you want to remove from the passage. You can then choose from three methods of filling them in on Learn Click. You can leave them open ended, select from a drop box or drag and drop the correct choice. Essentially you are creating an online interactive Cloze activity for your students and when they are finished they can check their answers to see how they did. Upgrading to a premium membership ($10 for the year) will get you unlimited quiz creation ability and also access to grades for each student who completes the activity online.
NEW!!! You can now export your cloze assignments to a .pdf file for posting on a webpage or printing.
Learn Click is a really simple site to use for cloze type activities. This could be a good resource for teachers with interactive whiteboards as well who like to use fill in the blank activities in class. Click here for an example cloze activity about WWII.