https://www.mymccard.com
As far as I remember the process goes like this
Go to a Rite-Aid, Vons or Albertsons that has a coinstar machine.
(See locator on website for closest one to you)
Slide some money in. I think 500 is max but not sure.
Receipt prints out with a pin/activation number
Call them up or activate on the website
You can use it online right away and card comes in mail later
edit: oh yeah you can upgrade it for $30 to $2500 limit and no block on adult sites