I was surprised when I saw the length of the Chrome user agent string last week:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.X.Y.Z Safari/525.13
And in our logs:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.29 Safari/525.13
a user agent string of 119 characters. It looks quite a waste of [...]

Logcheck is a tool to parse system logs and send summaries by email. It filters out logs with a regular expressions database to suppress common/normal entries.
Are you reading / checking your log files? Too many servers? logcheck will help you in this task and eliminates the noise.
Installing on Debian
# apt-get install logcheck
Reading package lists… Done
Building [...]

To rotate your nginx log files, you can use the log file handler provided by FreeBSD: newsyslog.
Configuring /etc/newsyslog.conf
/var/log/nginx-access.log               644  7     1024 *     JC /var/run/nginx.pid
/var/log/nginx-error.log                644  7     1024 *     JC /var/run/nginx.pid
Before log rotation:
-rw-r–r–  1 root  wheel    104278002 Jul 16 11:35 nginx-access.log
-rw-r–r–  1 root  wheel      1509531 Jul 16 11:17 nginx-error.log
After log rotation:
-rw-r–r–  1 root  wheel        967 Jul [...]

Cronolog is log rotation program which gives you a lot of options to template the log destination files. The common use is to split logs by year / month / day.
Here is how to configure Apache to send log entries to cronolog :
CustomLog “|/usr/sbin/cronolog /home/log/apache2/%Y-%m-%d_domain.com_access.log” combined
This will create a log file named 2008-06-02_domain.com_access.log for today.
Cronolog [...]