Andatool displays in realtime how often one or more regular expressions match with what scrolls-by in a logfile. That way you can see quickly, for example, what firewall-rules get triggered most.
0.8 removed debugging code
0.7 previous versions would use 100% cpu
0.5 one can now also list the matching patterns
0.2 now handles terminal resize correctly
0.1 initial release
MultiTail can also display this information while merging other data, filtering and much more.