Oh, hey, here's a device that I forgot about, the Peek: http://www.getpeek.com/index2.html

This article doesn't mention that there were actually four models - the Classic, Pronto, TwitterPeek, and 9 - but they were all very similar hardware anyway, with firmware being the biggest differences. 104 MHz ARM7, 8 MiB RAM, and tri-band GSM.

Their goal was to make a cheap e-mail-only device, with significant server-side assistance, although the TwitterPeek was Twitter-only, and the Peek 9 added a few apps for things like social networking and RSS. The result was extremely reminiscent of some of the earliest BlackBerry devices, like the 857/957, although using GSM instead of pager networks.