I carry a travel router. Those Linksys WRT54GCs are pretty good, a lot cheaper than the one with the integrated power supply and not significanly bigger or heavier.

As far as just doing business is concerned, I got more real work done with my handheld when I carried my Sony Clie. I could read and edit documents with Documents to Go, do some web browsing, even take the occasional audio or video note. I actually got fast enough with with Graffiti that could take notes in meetings.

Now, I carry a Lenovo X60 and my IT. I can't really take notes without my bluetooth keyboard, so I just open the X60 in meetings. Can't easily transfer documents back and forth either, so I just don't bother.

Don't get me wrong, I like my IT a lot - it's faster, has a lot more memory, and the web/email/IM experience is no comparison to the Clie. I just don't use it for business.