I've been considering for some time the options available in the United States for providing a home, home office, or small business with internet. I've worked now at multiple places which had multiple T1s (which are 'real' internet connections, with symmetric bandwidth allowances and service level guarantees), and I've known people with various connections at their homes - we've had DSL and cable internet, and other people I've known have had other, stranger beasts. My phone has high speed internet, some of the fastest available in the US, and I've considered the merits of using that for my home.
When I started seriously considering upgrading, this was the situation. Costs were high, speeds were low. Part of the reason I started looking was because I was moving, and my new location would have even worse internet than the place where I was living. Something had to be done.
It's very challenging to look at internet options, as the details are often not provided. Both Cable and DSL like to promote their download speed, not noting that, for example, VOIP (telephony) requires upload speed. Which they don't provide (AT&T's 'Elite' package gives a paltry 0.75Mbps upload at the time of this writing). On the other hand, their download speeds are quite competitive. A T1 provides 1.54Mbps in both directions, so you need four to get 6 Mbps (an oft touted number for both Cable and DSL at the moment).
In rural areas, Satellite is often touted as a solution, but with 1.5 Mbps upstream and 0.25 Mbps down, and high latency, it's not really functional for a number of standard internet functions, like online gaming and telephony.
EVDO Rev A and B are promising technologies. Rev A appears to be 3.1 Mbps down, 1.8 up (in theory) and B uses three channels to triple those numbers. This might be a good solution, however, indications are that high bandwidth usage will be charged big fees. Not ideal. Using my phone to test the connection, I found low latency, but a complete lack of the speeds touted, with both up and downstream slower than my current DSL
Wikipedia has an entry on future possible interfaces incl. WiMax. Unfortunately, these options are not yet viable.
Once you get past the 'consumer' grade internet, you move into the realm of 'real' connections: T1, T3 (DS1/DS3), Oc3 (155 Mbps), OC12 (622 Mbps). These are, to put it mildly, hard core. Special high-end equipment is required to connect to them, and they cost A LOT. On the other hand, it is hard to overestimate the speed of a true enterprise level connection. 6 Mbps, the current high-end consumer grade internet, is not even remotely the same as 6Mbps when composed of 4 T1 lines. More than one of my workplaces has had this level of internet to support several dozen employees.
The dark horse in all this is FiOS, a fiber-to-the-home (FTTH) service run by Verizon. Where available, it promises impressive speeds, including a mid-tier 15Mbps symmetric connection. Unfortunately, coverage is spotty, installing new areas is expensive, and it remains to be seen if the service will be seen as profitable (though since it also provides cable television, one imagines new installations will continue).