If you have a router model such as:
Linksys:
WRT54G v1-4
WRT54GS v1-4
WRT54GL v1.x
WRTSL54GS
Buffalo:
WHR-G54S
WHR-HP-G54
WZR-G54
WBR2-G54
WBR-G54
WZR-HP-G54
WZR-RS-G54
WZR-RS-G54HP
WVR-G54-NF
WHR2-A54-G54
WHR3-AG54
Asus:
WL500G Premium
WL500GE
WL520GU
Sparklan:
WX6615GT
Fuji:
RT390W
Microsoft:
MN-700
Then you are in luck. You can install custom firmware on it. These models are all supported by
Tomato http://www.polarcloud.com/tomatoThis can either be good experience or added functionality to that router. So it might just be still useful. If this does not satisfy your needs then feel free to check out the other
firmwares that are out there such as:
DD-WRT
OpenWRT
OpenWRT with X-WRT web interface(use google to find them)
which I have all used. I say
Tomato first cause it is one of the easiest and user friendly ones and the list of models here may not apply to the other firmware. Also like all of them say, try at your own risk.