I'm thinking about pure-wifi repeaters lately.  I came home for Christmas and my dad had gotten himself one of these:

http://www.amazon.com/D-Link-SharePort-Companion-Rechargeable-DIR-506L/dp/B0095F5ACE

It's pretty neat.  $45 and it has a battery and a special "wifi hotspot" mode, specially designed (supposedly) to deal with wifi hotspots that need stupid login pages.  The idea is you can use it in a hotel room and all your devices and share a single link to hotel wifi.

Now okay, I haven't validated the hotspot feature (they don't have a stupid login pages at my parents' place) and their UI is pretty awful and buggy.  But I like the idea and I like the price.  And it really does boost wifi signal strength when used appropriately.

Mind you they only have a 4 Mbit/sec Internet link here.  Repeaters use your wifi bandwidth pretty inefficiently, but you have a long way to go before 150 or 300 Mbit/sec gets all the way down to 4.