Megazoomer makes windows full-screen. Just press Command-Enter, and the front-most window grows to fill your entire monitor. Press the same keys, and it shrinks again. Requires SIMBL
With KeepNote, you can store your class notes, TODO lists, research notes, journal entries, paper outlines, etc in a simple notebook hierarchy with rich-text formatting, images, and more. Using full-text search, you can retrieve any note for later reference.