CDMA
CDMA data became available in my area in October of 1999. In November of 1999, I tried it out and was immediately hooked.
CDMA (Code Division Multiple Access) data runs over digital cellular networks (such as Sprint's PCS network). The protocol is apparently capable of supporting 56k data connections, but Sprint (my carrier) only installed 14.4k hardware (presumably to not stress their network infrastructure too badly on initial rollout).
As opposed to CDPD, which gave me 2400 baud performance over its 19.2 connection, CDMA really does feel like a 14.4 modem. The lag is nearly nonexistant, and I can see this scaling well up to 56k support at some future date. The price is fairly competative with CDPD for the amount of time that I spend transferring data (about 250 minutes a month), but the CDMA plans do not include an "unlimited usage" plan like CDPD does.
The newer Sprint PCS phones support a "minibrowser" - a web browser in the phone itself. I thought this was a rediculous concept until recently, when I realized that I should stop thinking of it as a web browser and start thinking of it as a two-way data service. I'm using a Samsung SCH-3500 phone; I used to use a Qualcomm 2700 (until it was run over by a car - or jeep, we're not sure which). I haven't gotten a data cable for the 3500 yet (I'm waiting for it to be delivered!), so I've been using the minibrowser (and some custom HDML - Handheld Device Markup Language - CGI scripts) to read my email via POP. It's not something that I want to do regularly, but it's certainly very portable, and I can see occasionally taking my phone with me to read email, but leaving my laptop at home. And I certainly can't create a custom two-way data source for my pager.
As a side note, the SCH-3500 has much better reception than the Qualcomm 2700. In areas where the 2700 wouldn't make calls, I get a fabulous signal on the 3500. There is also a problem spot in downtown Philadelphia (crossing Market Street at 34th) where the 2700 would always drop calls; the 3500 sails through them without problems.