I've been following Magnesium uses for awhile.
There's been some progress with absorption methods.
One is called magnesium oil, just magnesium chloride(mgcl) and water. It's applied directly to the skin.
The other solution is mgcl also but alcohol is used instead of water, usually vodka or everclear.
The benefits can be tremendous.
How to make: https://www.youtube.com/watch?v=WveaSB3D2-A
Some posting on the topic: http://ask.lef.org/15623/magnesium-bicarbonate-magnesium-acetate-benefits?PageIndex=9#bm16277
A blog recording how people have used it and benefitted. http://magaholmagic.blogspot.com/
I been using the mag oil version for about a year, I used to have occasional leg cramps while sleeping and suspected it was low magnesium.
I tried the oil and the cramps went away for 3-4 days with one application.
Besides all of this, magnesium is hugely important, it is involved in so many processes in the body.
Much more can be absorbed through the skin than orally. The limiting factor orally is spending time on the toilet, no more needs to be said here.