First: Thanks for your interest. Usage of the pool has grown enormously and the only way we can keep it easy for everyone to run a pool server is to also grow the number of servers participating.
Your computer must have a static IP address and a permanent internet connection. It's very imporant that your IP address doesn't change or only does so extremely infrequently (say once a year or less). The required bandwidth is relatively low. Each client will only send a couple of UDP packets every few to every 20 minutes.
Currently most servers get about 5-15 NTP packets per second with spikes a couple of times a day of 60-120 packets per second. This is roughly equivalent to 10-15Kbit/sec with spikes of 50-120Kbit/sec. The project steadily acquires more timeservers, so the load should not increase dramatically for each server. In plain terms, you probably need at least 384-512Kbit bandwidth (in and out-going).
Here are a few servers with traffic/load graphs: 1
The servers joining should not have pool.ntp.org as their upstream server(s), but should configure some good servers manually (those servers may be chosen from the pool. The point is that they are chosen statically instead of assigned randomly at each server restart. This will help providing an acceptable quality of service.) Note that it is not required that your server is a stratum 1 or 2 server - as this project is about load distribution mostly, there is no reason why a stratum 3 or even stratum 4 server shouldn't join.
We have a page with configuration recommendations for servers joining the pool.
Finally, I must emphasize that joining the pool is a long term commitment. We are happy to take you out of the pool again if your circumstances change, but because of how the ntp clients operate it will take weeks, months or even YEARS before the traffic completely goes away.
It would be nice (but it's not necessary) if you could redirect web requests on port 80 of your time server to the official web page of the project at http://www.pool.ntp.org. If you run Apache, you could do this with:
<VirtualHost *:80> ServerName pool.ntp.org ServerAlias *.pool.ntp.org *.ntppool.org Redirect permanent / http://www.pool.ntp.org/ </VirtualHost>
Again, this is only if you run a webserver anyway. The official project web page will always be given with the 'www' at the beginning - but sometimes people are lazy and just type pool.ntp.org and are then surprised to just get a random web page.