Here's a quick tip for travelers that travel with both a MacBook and an iOS device such as an iPad, iPod touch or iPhone. Although I usually travel with an Airport Express for those times when I'm in a hotel room with Internet access via ethernet, sometimes I'm in a conference center and I'm connected to the center's internet via ethernet directly into my MacBook Pro. In those cases I'm usally doing a software demo and my Airport Express is back in the hotel room. Also in those cases I'm usually either using my iPad/iPhone and/or I'm presenting with colleagues that also need internet access. The problem is that in those cases there are rarely multiple ethernet plugs and nor is there WiFi (well sometimes there's WiFi, but usually at an additional cost).
I do the next best thing
I plug the ethernet cable in my MacBook Pro and then I enable Internet Sharing via the Sharing System Preferences. This in effect turns your MacBook notebook into a temporary WiFi hotspot for other devices to share your internet connection. You can share any internet connection you have to the Mac over any other connection the Mac has built-in.
For example, if you are connected to the internet via ethernet, then that means you can share that connection over the Mac's built-in AirPort (WiFi) card. If you are connected to the internet via AirPort then you could share that connection to another Mac/PC over ethernet. This even works for those 3G USB data cards too. So if you were connected to the internet via a 3G USB/ExpressCard data card you could share that internet connection to other devices over ethernet OR AirPort. You can do any combination, you just can't share the connection you have over the SAME type of connection. So if you're connected via AirPort you can NOT share that connection over AirPort. Best of all if you share your connection over AirPort you can even password protect your temporary WiFi hotspot to keep others off your connection and from stealing your bandwidth.
My boss was very appreciative of the fact that when we were in London and I was presenting, she could be in the audience with her MacBook Pro and catch up on email "wirelessly" during the breaks since I had the only ethernet connection, on stage, as there was no other WiFi connection in the venue.
Remember to turn it OFF when you're done
When you're done sharing your internet connection over AirPort you will need to go back in and STOP sharing the connection when you're done. Otherwise you will not be able to access the internet over AirPort again until you do. Your AirPort menu bar icon will change to a sharing icon to serve as a constant reminder that you still have Internet Sharing on.