There really are none that can "prep" you for law school.
And I vehemently disagree with Unbiased Observer's suggestion about reading E&E books. Don't do it. There is virtually no gain to you and a lot of risk like thinking you already know the material, looking like an a-hole to your classmates, etc. If you want to keep your mind sharp, read some good periodicals like NYT, WSJ, Economist, etc. But take it from me as a recent graduate (and currently preparing for the bar), you are wise to savor the weeks before law school begins and relax and enjoy the freedom you have while it lasts . . .
To each their own. However, I would strongly encourage the use of the E&E's and other study guides. They do a great job of getting you to think about law school hypos, and illustrating the exceptions to blackletter law.
I would also strongly recommend signing up for the LEEWS seminar and purchasing the LEEWS Exam Primer. This helped me significantly and I was top 10% at a top 20 largely in part to the help and direction the LEEWS seminar gave me.
Hope this helps. Good luck.