For any geek stuck in a long car trip or a vacation in the middle of nowhere, a laptop with an internet connection is the holy grail. We're always stuck in these situations and thinking, "Man, if I had internet access right now, I could be doing all sorts of stuff. I'd never be bored."
If we're driving, we're SOL (unless we want to do something incredibly stupid and dangerous, like watching DVDs while driving). But when we're passengers, and when we're actually at the vacation spot in the middle of nowhere, we have absolutely nothing to do.
The first step is to get a laptop. That's not too outrageous nowadays, since many geeks are finding that laptops fill their hardware needs perfectly well at a reasonable price. But once we're disconnected, all we can do is stare at the wallpaper with nothing running and think, "What did I do on my computer before the internet?"
Cellular providers have offered PCMCIA cards for a long time, but they've usually been $300 with awful data plans that charged per kilobyte. These were about as useful as the Palm VII (have you ever seen anyone with a Palm VII?).
Cell phones usually have data cables available so they can be used as modems. Some phones have Bluetooth, which usually allows modem use by a Bluetooth-capable computer without any additional equipment (although the price difference between a Bluetooth and non-Bluetooth phone could buy quite a few data cables). By the way, Bluetooth is a huge buzzword in the gadget market. It's supposed to revolutionize everything. But hardly any consumers really know what it is. Basically, it's like wireless USB: a wireless communication standard for devices to connect to each other within a few feet.
Once the phone is connected to the computer, you usually have to dial a special number (#777 for most 3G phones) and you get direct internet access. Data access is billed differently by carrier - for example, Sprint and AT&T charge per kilobyte, and Verizon uses "minutes" as if you were talking on the phone (free after 9 and on weekends). (NOT ANYMORE - see update above) The other carriers offer unlimited plans, but most are around $80 per month, with the notable exception of T-Mobile, who charges $20 for unlimited access if you also have voice service or $30 for data-only service.
Verizon's older service, Quick2Net, is a basic CDMA service, offering a blazing 14.4 kilobits per second! Fortunately, their newer phones support the Express Network, a 3G 1X service at 144 kilobits. They have a higher-speed service called BroadbandAccess that supposedly gives a 1- to 2-megabit connection, but only in a handful of big cities so far, only using PCMCIA cards, and only with an $80-per-month unlimited plan.
After using the Verizon Express Network through my LG VX4500 on a Powerbook for a few months, I have arrived at an incredibly dull conclusion: it's good, but only for limited use.
The phone's battery life isn't much of an issue, since the data cable can be connected while the phone is in the charger, essentially giving unlimited battery life. Otherwise, using the phone as a modem drains the battery life slightly more slowly than making a voice call - it saves a bit of power by not using the speaker, and the phone can be closed so the internal screen stays off.
The phone has a helpful "feature" that suspends the connection if it's idle for about 10 seconds to save airtime. But then, the next request needs to wait an extra 5-10 seconds for the phone to reconnect. It's not worth it, and there's no way to disable it. Fortunately, you can get around it fairly easily by opening a terminal window and telling your computer to ping somewhere (like google.com) every 5 seconds. This doesn't noticeably slow the connection, and it prevents the phone from suspending it.
The connection itself is usable for basic internet use - browsing pages, checking email, and using instant messages can all be done simultaneously without any noticeable slowdown. You can even load two web pages simultaneously without an unreasonable performance loss.
Bandwidth is great for a cellular connection. With full reception, the Broadband Reports speed tests tell me that I'm actually getting about 120 kilobits per second of useful bandwidth - close enough to the advertised bandwidth. The upstream gives me a sufficient 30 kilobits per second. These numbers didn't significantly change with the keep-alive ping running.
The main problem is the connection latency. My pings to keep the connection alive averaged around 500 milliseconds, while the same pings on my home DSL connection only took 35. The high latency impedes some internet-connection uses such as multiplayer action games or remote computing (through Remote Desktop or text consoles).
Like all cellular data connections, bandwidth and performance drop considerably as signal reception decreases. The connection is almost unusable with 3 bars or less (out of 6). If you're regularly in areas with poor reception, don't get your hopes up. Of course, my VX4500 drops calls regularly when reception is that bad, so it probably wouldn't be a huge surprise to have unreliable data service.