I have two
D-Link DIR-655s. One at home and one at my girlfriend's house. I find them to be excellent, and I can count the number of times the signal has dropped in the last six months at either house on one hand.
Also: the antennas are removable and D-Link does sell a
compatible external antenna, but I don't think its high gain.
Here's the caveat: Second generation iPod Touches and iPhone 3Gs can't connect to D-Link's newer routers when using WPA. I'm not sure if the fix will come from Apple or D-Link, or whether it will come at all. Presently I have a secondary guest-zone setup on my router with a WEP password that my sister's iTouch connects to.
Seems that the WPA problem with the iPhone/iPod Touch has gone away. Must have been the 2.2.1 update from apple.