Do you have a great idea what a router should be able to do, but you cannot make it work because you can't tweak router's embedded management tools (including Tcl)? Here is an opportunity you shouldn't miss: enroll in the Cisco AXP Developer Contest. Even if you're absolutely positive that having an extra Linux server sitting next to the router is better than a router blade (and some Linux pundits had lots to say on the topic), sending your ideas to Cisco won't cost you more than a few moments of your time and an e-mail ;)
And, BTW, mundane (but nonetheless highly useful) ideas like »visual policy map editor« or truly integrated DNS/DHCP server probably won't get you very far (that's why I'm not applying :).
Full disclosure: I was kindly asked if I could help spreading the word about the contest, but all the enthusiasm is exclusively mine.