Spending vacation at the summer house without Internet connectivity? Unthinkable.
The first few days, I connected the laptop to my cell phone using Bluetooth, and then to the Internet using 3G/UMTS.
However, we have more than one laptop here, and the range of bluetooth is limited. I ended up setting up a wireless access point with a PCMCIA slot for a 3G/UMTS card. It has worked flawlessly for several days.
The writeup on how to do this is long, so I put it at a separate page:
Update: I have written a similar howto for OpenWRT 8.09 and Huawei E220, see http://josefsson.org/openwrt/dongle.html