Based on where you are at Law School, my guess it it will not help much, b/c a lot of your competition will have the same thing on their resume.  If you were at a Texas, WashU, or equivilant, you would likely stand out more.  My two cents

"My only interest: Lifelong fan of the Xs, the professional Y team in your office's Metropolitan Statistical Area"

Just don't apply to any NYC firms.

Jets v. Giants?
Mets v. Yanks?
Nicks v. Nets?
Rangers v. Devils?

500 pages white paper = $20 (for writing samples [when requested], and unofficial transcripts] ... some of this is excess/left over
175 nice "resume" envelopes = $15 for a pack of 25 * 7 = $105 (I might be wrong on this one; can't remember)
400 sheets of 100% cotton paper = Four 100pg packets costing $20 each = $80
180 stamps * .40 cents per stamp = $72
2 ink cartridges @ $35/e (office depot didn't have the ink to refill my printer cartridge) = $70
Total = $347

Getting a summer job in this economy...Priceless

When it comes to improving grades, select your professors and, more importantly, exam grading style varefully.  If you are a below average typist, don't select professors who reward a "brain dump" by grading with a check-mark system.  If you cannot type as fast as others and end up with 5 less pages, that is five less pages worth of check-marks.  On the other hand, if you are an above average typist, the converse is true and will play to your advantage.

A couple of things worth noting.  While I am not a JAG, I am a former Army Company Commander and worked with the JAG office all of the time.

1) If you are not competitive for some of the BigLaw salaries, the JAG may offer more money than other jobs.
    a) you get a tax free housing salary based on where you live.  As a married Captain in Virginia, my last duty station, the housing allowance was $1887 for 2009.  That's over $22,000 annual, tax free.
 
2) You get a ton of experience.  The JAGs I worked with, were trying cases in court rooms, and after 3 years will have a ton of experience other laterals may not have.  Not to mention, the military thing looks great on the resume.

3) You experience a lot of different aspects of the law.  If you are not sure what you want to do for your career, this may help as well.  I sent soldiers to JAG for issues raning from criminal, family, tenant, contract, etc.


Obviously, there are cons
1) For some people this is tough, but you need to uphold yourself to high standard (good fitness, clean cut, no drugs, no DWI, etc.)
2) Deployments - if you are married, they can wear you down.  If you are single and don't have to deal with the family aspect, not as much.  Either way, deploying is one of the most rewarding experiences of my life.  And again, looks good on the resume.
3) Pay is not as good as BigLaw, but the hours aren't as long, unless you are deployed.

Hope this helps with anyone considering JAG.  If I had to choose, I'd say go Air Force.  They seem to live the most comfortable lifestyle.