Thank god for my normal, nice, not creepy tutor. She turned me on to the best math review book ever (if your problem is verbal, I can't help you. I'm mathtarded).
It takes you through everything from arithmetic to geometry, with practice problems after each lesson for reinforcement. I hate math, but I love this book. I am actually feeling sort of confident now.
Another good tool is Cramberry if you're into flashcards without actual flashcards. I really liked this until I realized that I couldn't do it on the subway.
Did you know if you google "GMAT" and "depression" you can find some free GMAT flashcards? It's true!
And finally, my mantra, which I stole from someone else: Quick, Calm, Careful.
I'm a big believer in mantras. They got me through the marathon, and really help to shift your emotional state if you're a sensitive type like me. Hope this helps!