I've become a bit obsessed with getting cellular data on USB modems. I travel a great deal, and having a USB data modem has saved me money over the long term since I don’t have to pay $15 or $20 per day if I am in an airport or hotel, for example, and need to check my email.
I bought a Virgin Mobile Ovation MC760 USB data modem about two years ago from Walmart. It cost about $100, and the good thing was that Walmart had an arrangement with Virgin Mobile so that a Walmart-purchased modem offered better and cheaper plans than Virgin Mobile offered. I still have the modem (anyone want to buy it?) and it offers a one-month plan that allows 1Gb of data, for $20. Virgin Mobile has since raised their prices; the nearest equivalent plan is $35 per month for 2Gb of data.
The only problem is that Virgin Mobile uses the Sprint network, which is not available in some places. For instance, we have a summer cottage in Washington state, and I can’t get internet access there using the Virgin Mobile modem.
I also have tried a Datajack Mifi hotspot, and this is a great service and a great little device. The Mifi hotspot is dead simple to use and set up. It has a battery and lasts quite a while. If I am in a hotel room and need the internet, I can just put this on a table, turn it on, and in a few seconds, I will have my own wifi hotspot. The speeds are fine as is the prices. Again, however, the problem is that the Datajack service uses the Sprint network.
A last service and device that I heartily recommend is the FreedomPop service. I am often at my parents’ house in the Bay Area on the weekends. They don’t have internet service, which sucks. When I am there, I just plug this stick into my Mac laptop, and I have internet service from the Clear network. The FreedomPop stick works well when I am in the Bay Area,, and they offer a free service. I just paid $50 for the USB modem which they call a “deposit” and which gives me 100Mb per month free. However, like many free services, FreedomPop often sends bogus marketing materials stating "free upgrade" which are nothing more than ways to get you to pay. If you can sidestep the marketing ploys (which are downright fraudulent!), this is a good free service. It’s fairly slow during the day, but I have found that it is pretty fast in the evenings. Again, the big problem is that the Clear network is so limited (I cannot get it at our place in Washington state, for instance).
I have tried more gear like the above, including a Zoom modem for AT&T SIM cards and Cradlepoint routers. I’ll write more about my experiences shortly. In the meantime, a great resource for information on these kinds of things is the 3G store: http://3gstore.com/ -- “Official Site for all things 3G”.