QMentat helps you practice mental arithmetic. It uses arbitrary-length fixed point arithmetic, and can handle any size numbers, only limited by the size of your screen (and in the case of division with an integer result, the speed at which the number can be factored). It is also quite configurable, allowing you to tailor the questions to your needs.
Fresh Memory is an application that helps you to learn large amounts of any material with Spaced Repetition method. The most important subject is learning foreign words, but Fresh Memory can also e used to learn anything else. Other examples are country's capitals and flags, chemical elements, mathematical formulas, and technical terms. The learning data is stored as flash cards and dictionaries: sets of cards. The flash cards may have several fields, and the user controls what combination of fields to learn. The flash cards can have formatted text and images. The look of flash cards and studying parameters are can be flexibly adjusted.