We do get this sort of crap daily at least 5 times a day, distributed tcp/ack, tcp/syn, etc, over 40-50Kpps+ sometimes.. my list of over ~230 slave networks (in /24 format). Kids are after taking CPUs in routers out and not killing you with hundrends and hundreeds of Mbps, high-pps attacks are also very nasty, and of course everything is over some stupid IRC issue.
We have found two hacked Linux boxen (on customers boxes) recently that have been used as DDOS creators. Both were older (Redhat 6.0) and were well hacked, replacing ls,find,ps,login,wtmp.. etc... and they installed a small IRC proxy server (BNC ala bnc.com) and then some tools for sniffing and apparently creating DDOS. We were unable to find traces of the originating IP's in logs or other files. I saved some of the programs (t0rnD, stachel..)