Hi Ann,

There are more companies than these, but this is just a few.  These also do not require a contract.

T-Mobile $70/month unlimited talk/text/data

MetroPC $40/month unlimited talk/text/data

Straight Talk $45/month unlimited talk/text/data

Virgin Mobile $55/month unlimited talk/text/data 

I know a quite a few people using these services for quite a while and don't have any complaints.