Just want to note that Eligius has been under constant DDoS attacks for well over a week now. Mitigation sometimes requires temporarily killing one or more public facing IPs and letting miners reconnect to others. As long as you're using the proper hostname, stratum.mining.eligius.st, then your miners should do all of this automatically.
What a ball-ache wk - how can you mitigate against this kind of anal attack... More servers is all I can think of... Keep up the good effort!
Mitigating DDoS attacks is pretty basic, depending on whether they're trying to attack the TCP stack (like SYN floods) or the protocol (like that NTP reflection attack that was going on a couple of months ago). More servers won't help unless you have a genuine scaling problem.