PowerVocab Adv Reader Pack
This app contains a database of over 700 commonly tested words and presents them in a multiple choice format, just like on the tests.
Kaplan GRE Exam Vocab
500 more words to learn. This app also gives you a sample sentence and phonetic pronunciations of the word. The app sells for $5.00 and contains all the same flashcards as the $20.00 physical pack.
This app contains over 6000 words and bills itself as being good for more tests than the GRE. Word lists also from: SAT, LSAT, PSAT, ACT, GED and more.
Learn Math via Videos
This one is for brushing up on all those old formulas you learned back in high school. Has sections for geometry, trig, calculus and more.
This is a simple collection of all those pesky grammar rules. Includes rules on punctuation, capitalization, commonly misused and misspelled words and more. Also gives you proof-reading tips for any tests out there that include an essay portion.