I was in the Doc's office and picked up a magazine, tonight was spelled tonite, I see that a lot, how and why did this come about and is now acceptable to use?

I've no idea how this started, kitty, but I suspect it is a piece of "eye-catching" English like Krispy Kreme or Dunkin Donuts such as featured in a thread here recently. Check it out at this reference.

The M-W dictionary at the top of the page does not recognise it, but suggests tonight, while the Atomica GuruNet dictionary goes straight into tonight, so I reckon my own feelings are correct, that tonite is an abomination.

The M-W thesaurus does not recognise it, but suggests other spellings, including tomato!