I'd like to use voice-over-ip (e.g. Vontage) where no wired internet
connection is possible.  I have a small box that connects to the
internet with a typical ethernet cable, and has a phone jack that
gives a dial tone when everything is working correctly.  Is there any
way to go from the wireless connection on my laptop via an ethernet
cable to the voice-over-ip box?  Just plugging it in to the jack on
the laptop doesn't seem to work, since it's expecting an input
connection FROM the internet instead of an output connection TO the
internet.  Do I need to configure the laptop differently, or do I need
some sort of a router in between, or is the whole thing impossible?

You may wish to try setting up Internet Connection Sharing on that
port. For that, try this article from Microsoft:
http://support.microsoft.com/default.aspx?scid=kb;en-us;306126

Hopefully your Vonage box will automatically detect IP address
settings. An alternative that wouldn't require your laptop, but would
use your existing wireless connection, is a "Wireless Ethernet
Bridge", like this one from Lynksis:
http://www.amazon.com/exec/obidos/tg/detail/-/B000066JQU/104-9627709-1898357?v=glance

Set this up with your wireless connection (you may want to configure
it using your laptop), and it's like an extended ethernet port, you
should be able to plug right in.

Try the Internet Connection Sharing first, their are plenty of guides
online on this topic. If you can't get that to work, or wish to use
Vonage without a laptop, the Bridge should work. Good luck.

Matthew Rasmussen