Grep (aka lastlog) command
Grep command (/grep, /lastlog) allows to quickly show messages from the history which contain given text. Optionally you can limit it to the N last, most recent messages. Command is similar to the /lastlog which is present on some irc clients.
Usage exmaples:
/grep something
/grep something 5
/grep "two words" 5
/grep -l 5 "something else"