Having some sort of built-in WWAN - like EV-DO or HSDPA - can make a world of difference if you're in dire need of an internet hit but out of range of a WiFi hotspot. However, it does mean you're at the mercy of cellular signals. Samsung Q1 Ultra owner Andyman had already stuck the miniPCI-E guts of a USB EV-DO modem into his UMPC, but was fed up of mediocre coverage when in remote locations; what better excuse to slap a great big external antenna on and enjoy full signal everywhere!
Andy himself admits that it's a rough'n'ready hack - primarily because he limited himself to parts he had lying around - but the proof of the pudding is most definitely in the indigestion it gives you afterwards and in this case it's a whole stomach-worth of top notch EV-DO at plentiful high speeds.
"I dive regularly and locations I go, I get hardly any cell coverage. I needed an antenna with decent gain and with the ability to use external antenna. Needed to be removable too ... I get full signal strength everywhere. If I remove it, I get 2 - 3 bars"