I have no landline and use Mediacom cable as my ISP. I package it with my cable. Our total bill is usually around $100 with the internet costing about $50. You can also get satellite, but I think that costs more and is unreliable.
your best bet (without gettin complecated) is to get a USB dongle there avaliable fom a variety of suppliers e.g O2 vodaphone. Best one out atm is the vodaphone package:
1) pay as you go - one off payment of around £30-50 then monthly payments of £15-20 depending on your useage.
2) contract (connections no better, dont let them fool you!) just no initial fee (but your tied down and a better one may come along)
WARNING! no matter how good your connection with dongles they all arnt fast your talking and ave of say 2.8mbs