I live in a big house (no, not The Big House, a prison).
I have a "phone room" in the basement filled with lots of phone and network equipment, including a NetGear wireless router.
I often use my iPad on the second floor. It works fine in the master bedroom, which is above the phone room. If I try to use the iPad on the desk in my office, which is also on the second floor, but about a 30-foot horizontal distance from my bed, the signal strength is very weak. Sometimes I can't connect to the Internet at all, and book and music downloads are usually impossible.
I found an inexpensive and easy solution. The Netgear Universal Wi-Fi Range Extender (WN3000RP) is a compact white box that plugs into an electrical outlet in my dining room, on the first floor, above the phone room. It relays signals between my iPad and the router.
It's truly-plug-n-play. There's no need to install software, experiment with different switch settings or even to RTFM. Price from Amazon is $66.53. If I had known about this a month ago, I would not have needed to make a wired network connection for a TiVo box that can use a wireless adapter.