Wireless Ethernet
In the summer of 1998, I worked on a project for the University that involved wireless ethernet in a classroom. We decided to use the (then new) IEEE 802.11 protocol; the first convergance of the plethora of divergant wireless ethernet standards.
We worked with NetWave 802.11 FH gear (now the BayStack 650 line), and set up a classroom full of Toshiba Libretto 100CTs with NetWave cards, connecting back to two NetWave Access Points (hubs). The project worked out fairly well, and NetWave was bought out by Bay Networks who was bought out by Nortel Networks. Success in America - if your company becomes prominent enough, someone else might buy your company!
On the down side, it took about 9 months before the 802.11 firmware was solid enough to keep the hubs from crashing every 3 or 4 days. It seems that they've finally got it right, now that 802.11 has moved on to 11 Mb devices.
On the up side, I put together a wireless network in my house. This is the most liberating technology that I've come across recently: instead of being cooped up in my den, I can sit anywhere in the house and keep working. Of course, I still wind up in the den most of the time...
The devices available roll over so quickly that it's useless using anyone's suggestions as to what's best without re-doing your own research. These are a dime-a-dozen now (in 2006).