apache logs in a load balanced cluster
 

I have 3 apache web servers behind a load balancer each server writes weblogs to:
/etc/apache2/logs

and I have them rotated as access_log_srv1.gz , access_log_srv2.gz and access_log_srv3.gz (for example) than I move the logs to be processed in urchin 7 for stats :)

can I have one shared log that is written of a NFS mount or is there a simple way merge the 3 daily logs to one file?

yes there is, it's called syslog. Once you have that set up you can do loads with it!
Basically it's logging to a central server.