Use protection on open Wi-Fi hotspots:
The time you save by logging in to the first unencrypted Wi-Fi hotspot you encounter doesn't compare to the risk you take if someone shady sniffs your password or hijacks your Gmail session and steals all your personal info. You can reduce your risk by using utilities such as Hotspot Shield and configuring your Web apps to use HTTPS whenever possible, but you need to take those steps before you log in to the unprotected Wi-Fi spot. Read "How to Stay Safe on Public Wi-Fi" for more security tips.
Come down from the cloud:
It's easier than ever to keep your work in the cloud without disrupting a traditional work environment--that is, until someone pulls the plug. Make sure to have a solid set of offline tools so that you can still work when you're disconnected, and keep local copies of anything business-critical (your schedule, for example). Maintaining a record can be as simple as saving a Google Doc as a Word doc, or taking a quick screenshot of your to-do list on your smartphone before you head to the airport.
If you depend on Google services, grab Google Gears. Even though Google effectively abandoned it more than a year ago, it still allows you to access your Google Docs, Gmail, Google Calendar, and a few third-party apps like Remember the Milk without an Internet connection. It's already built into Chrome, but it also supports Firefox and Internet Explorer in Windows, and Firefox in OS X.
Bring a better Wi-Fi stumbler:
Still using Windows' built-in Wi-Fi panel in the taskbar? Before you hit the road, pick up a more powerful utility such as NetStumbler or InSSIDer. Unlike Windows' built-in Wi-Fi signal meter, these apps will give you a good look at which networks have a consistently strong signal over time, which networks are on overlapping channels, and so on. This information is particularly useful when several usable networks are in the area and you want to know which one will give you the best reception without having to try them all out one by one.
Try to find the Wi-Fi access point:
Even the fastest Wi-Fi cards can't help you if you're too far from the access point itself. Try to find the actual hardware access point itself, and sit near it. In public spaces, check near any labeled "charging station" areas and scan the ceiling for any boxes labeled with networking equipment brands (Cisco, D-Link, Netgear, and so on). Coffee shops often have them in plain view near any phone/ethernet wiring. If you can't find it, you can use the Wi-Fi scanners mentioned above to check your signal strength while walking around the room, though you'll look like you're using your PC to dowse for water.
Plan your trip with Internet in mind:
An easy way to avoid getting stuck without Internet access: Do your homework. Don't book your hotel reservation without checking the HotelChatter blog's most recent Annual Hotel Wi-Fi Report, which provides listings of free, paid, and free-with-membership hotel Wi-Fi access. Kayak also has airline, airport, and hotel Wi-Fi comparisons. Plan your trip right, and you'll be able to work from everywhere after the TSA checkpoint.
Starbucks is your best friend:
Regardless of what you think about the chain's coffee, you'll be elated to find a Starbucks when you're desperately hunting for Internet access. The same goes for McDonald's, Panera, and pretty much any hotel lobby. Even public libraries usually have free Wi-Fi--whether they're open or not. You can check out free Wi-Fi databases such as OpenWiFiSpots.com before you leave for your trip, but the listings aren't always accurate or up-to-date, so you're probably better off just noting where your coffee-shops-of-last-resort are. If you're really worried, invest in a membership with some of the more common Wi-Fi providers, such as T-Mobile HotSpot.
Have your own tips for disconnected road warriors? Share them in the comments!