CradlePoint mobile routers. They take EVDO/HSDPA/etc on one side, and spit out wifi. So, little stompboxes.
First: CTR-500. $160. Works with expresscard or usb wireless modem. has an ethernet port, which I understand can work either as wan (if you're somewhere you can get wired ethernet) or lan (sharing out the wireless connection to a wired network).
Second: PHS-300. $150. USB only. No ethernet port, no expresscard. BUT, it has a builtin l-ion battery. On the other hand, a quick search of reviews says the battery only lasts about 2 hours. That's /acceptable/, but I'd prefer more. If I get the CTR, I'd have to build (or have built) my own battery pack for it, and would aim for better battery life.
Main usage pattern would likely be something that spends most of its time living in my backpack, connected to a dedicated wireless modem. run a cord out the headphone hole on the backpack to plug it in at night (or whenever possible).
I paused while writing it to go update my little list of what prices the locally-covering wireless carriers charge for their unlimited data plans. And what did I find out? They don't. Of Sprint, Verizon, AT&T, and T-Mobile, only T-Mo still offers an unlimited data plan, and they're only EDGE. The others all cap at 5GB/mo. Presumably to prevent you from running bittorrent and other p2p crap over their precious networks.
My grand plan was to drop t-mobile's data service and switch to a high-speed network, use the stompbox to share out that connection to all of my devices (laptops, N800, iphone, everything) wherever I am, and go happily about my way.
Now, I don't know what sort of bandwidth I'd use. My iphone is currently reporting 26.9mb sent and 236mb received, which is either since I started using it (seems low) or since I upgraded to 2.0 on the 29th (seems high, but not hugely). I'd probably use a little bit more than I currently do if I had the new setup, due to using it with other devices as well. So, would the 5gb cap be a problem? I don't know. I kinda doubt it.
But that's not the point. I'm not willing to pay more per month for 'broadband-like speeds' if it's got a byte cap. I'm not willing to pay for a connection with a byte-cap at all, frankly. It's the principle of the thing.
So, this plan is mostly scrapped. I'll probably still buy one of the routers anyway, at some point in the future, but whatever urgency there was to doing so, if that word can be applied here, has gone.
edit: I should note also that, while I didn't make a note of the current pricing for these unacceptable plans, I seem to recall that they're priced more or less the same as the old unlimited plans. I'd have to go look, but can't be bothered at the moment.