Middlespot.com is a websearch interface that is specifically designed to help you manage your online research. The site doesn't require a login nor are there any plugins that need to be downloaded. This is a benefit on the one hand especially if you are planning on using it with k-12 students but there are some potential drawbacks to this that I will get back to in a moment. Let me explain the basic features of Middlespot first.
Users can conduct keyword searches with Middlespot and view their results both as text, similar to what you would see in a Google search, and as a series of thumbnails. You can then save different sites to your workpad and add annotations to each site you save. The workpads can be e-mailed to friends to share your research. These workpads are also saved for you and available the next time you visit the Middlespot site. This is where using a tool like this on a public computer, such as the computers in your school lab, becomes problematic and I would rather have the option of signing students up for their own accounts so that they could create and access their workpads individually. To learn more about the tool you can go through the slideshow included below, which comes from the help section on their website.