|Great Comet Over The Acid Hills. (Photo credit: @chris)|
Almanacs - An extensive calendar containing important dates and events. Always good to know when the next comet will come or what the weather is predicted to be.
Biographies - Quick and short descriptions of some of the most notable people in human history. Great when reading other biographies or general history text.
Calculators and Conversions - Just some basic calculations for converting between units and general math calculations. Always great when working with any sort of numbers.
Dictionary and Thesaurus - Nice when writing anything in particular or reading a book. Gives you the opportunity to expand your literature knowledge.
Maps - When uncertain about geographical information.
Citation References - A must when writing a report or paper. Different methods require different means of referencing others, and it is good to know what style is appropriate for a certain situation.