The Differentiator is a simple web app that helps you create objectives based on Bloom's Taxonomy. You simple click on the thinking skill, content, resources, product, or group tabs and then select what you want the student to do by clicking on the sub categories.
For example, on the Thinking Skill tab, you can chose Remembering, Understanding, Applying, Analyzing, Evaluating, or Creating and then a sub-term. Product tab has visual, multi-media, oral, written, and construct tabs as what the student would create as a product to demonstrate their learning.
I think this is a great tool to help teachers come up with different objectives and some different activities for students to do in class.
Related:
Differentiation Using 21st Century Schools
Differentiation with Web 2.0 Technologies