I have recently replaced my TP-LINK (used as a temporary replacement for my old Linksys, which has met it’s demise) router with Asus RT-N66U and added a Gigabit switch to upgrade my home network to Gigabit.
RT-N66U is a really decent router. It’s OF (called AsusWrt) seems to be based on Tomato and is open source. The OF also supports Optware OOB (uses Oleg feed) and can install apps directly from WebUI.
Another great feature is Telnet access, which enables to directly control the underlying Linux OS without using the WebUI (most routers do not have this feature, even though they run Linux as their OS).
I am currently using a slightly modified version of OF, which enables some nice features, like a writable flash partition (separate 13MB JFFS partition), startup applications, etc.
Since this router has enough power to run both my routing and my network apps (BT, Samba, etc.), I have retired my custom modded Belkin modem-router (which ran a modified version of DD-WRT) and moved all my network apps to RT-N66U.

Although the Web UI is nice, I have setup most of my apps from Linux terminal because I needed a greater degree of customization than that offered by the web interface.
Using a terminal allows you to customize all configurations directly and allows you to do more than just routing and running network apps. I have even installed Debian’s MIPS port (in chroot) which, with it’s wast collection of apps, offers endless possibilities (heck, I can even install gcc and build apps from source directly on the router).
I have even tried TightVNC with LXDE desktop ! (Just for fun. The desktop is pretty slow though, too slow for anything more than playing solitaire and light web browsing).

On the hardware side, the WiFi range is also great, much better than I expected. 5Ghz WiFi is nice too (especially combined with my 5Ghz capable Linksys AE3000 dongle), too bad it’s range is very short.
I also like 256MB RAM, dual radio WiFi (with three antennas) and onboard MicroSD slot (too bad it’s installed in a way that it cannot be used without voiding the warranty).

Technical specs of RT-N66U:
CPU: Broadcom BCM4706 @ 600 MHz MIPS
RAM: 256MB
LAN: 4xGigabit LAN, 1xGigabit WAN
WLAN: 2x Broadcom BCM4733, 2.4Ghz and 5Ghz capable.
USB: 2x USB 2.0
Storage: 32MB onboard flash, internal MicroSD card slot.