Remember my post about stopping comment spammers with Javascript? It has proven to be a very reliable method as long as you make sure to change the data that is generated with Javascript from site to site. A little example of only today from "spam that didn't quite make it":

[root@rbox /]# cat /var/log/randombase.com.log|grep "POST /news"
87.255.64.233 - - [19/Apr/2008:01:18:31 -0500] "POST /news/33 HTTP/1.1" 200 8922 "-" "-"
87.255.64.233 - - [19/Apr/2008:01:18:35 -0500] "POST /news/33 HTTP/1.1" 200 8922 "-" "-"
83.247.31.93 - - [19/Apr/2008:02:12:29 -0500] "POST /news/33 HTTP/1.0" 200 8811 "-" "-"
83.247.31.93 - - [19/Apr/2008:02:12:31 -0500] "POST /news/33 HTTP/1.0" 200 8811 "-" "-"
85.232.230.225 - - [19/Apr/2008:03:10:46 -0500] "POST /news/33 HTTP/1.1" 200 8924 "-" "-"
85.232.230.225 - - [19/Apr/2008:03:10:48 -0500] "POST /news/33 HTTP/1.1" 200 8924 "-" "-"

In this case it is clear they tried to spam us, no useragent nor referer set.