From Yigal Agam:
Web Page Splitter is a utility that creates framesets with Web pages of your choice, enabling you to view multiple pages in one browser window. You can create as many frames as you like, adjust their relative size and assign a url to each frame, and then create an html file containing all those frames in one split browser window. Practical applications include, for example, having a multiple-frame page contain your favorite news websites, stock quotes or general web portals. Web Page Splitter supports drag-and-drop straight out of your browser's address bar.