axe is a command line utility that makes parsing logs easy as you develop.
gem install axe
$ axe
> tail -f log/development.log
$ axe active_record
> tail -f log/development.log | grep active_record
$ axe active_record action_view INSERT
> tail -f log/development.log | grep "active_record\|action_view\|INSERT"
$ axe -e test
> tail -f log/test.log
$ axe -e test active_record action_view INSERT
> tail -f log/test.log | grep "active_record\|action_view\|INSERT"
$ axe -n 50
> tail -n 50 log/development.log
$ axe -n 50 INSERT
> tail -n 50 log/development.log | grep INSERT