I used these many times. The best two options are
Netspend and Greendot
I for one am all for Green Dot. Go online and sign up for one (free) it comes in about 2 weeks with your name ( you can buy one at wallgreens for like $5 but you still have to reg to get one with your name) at go to wallgreens and by reload packs. There is a $5 fee per reload pack. The limit is I think $1500 on the card.
Netspend is ok. You can go to like a pay day loan place and add money I think it is $2.50 to do this if i remember correct. They are ok but I like green dot far more. Net spend was kind of a pain to set up.
Hope this helps for those who are worried they wont have enough in the bank when they "win" or do not have a credit card.