Hey
surfingpirateIMO, you could use eGMAT (GMAT Online) to improve your understanding of
GMAT Verbal and Quant. There are 90+ hours of Verbal Video Lessons and
40+ hours of Quant Video lessons. This package costs $299.
They also offer the GMATClub Prep tests free with this package which is an
awesome resource for improving your Quant skills. There are some 1300+
Quant questions which should be enough practice to improve your Quant
skills!
You could also check these links for more GMAT Quant related information
1.GMATClub Quantitative Mega-Thread2.ALL YOU NEED FOR QUANT ! ! !3.PS Directory by Topic and Difficulty4.DS Directory by Topic and DifficultyThe third and fourth links are for additional practice.
The GMATPrep tests are slightly tougher than the real thing.
My advice would be to start with the third and fourth links after you have
a clear understanding of the concepts(which you should have by studying
from the Manhattan Strategy Guides/eGMAT and supplement it with the 1st
link)
Hope this helps you!