Contool will capture and display system console messages with timestamps.

It is a replacement for the standard X console.  Contool will flash its
icon and beep when messages are written to the console, so you can keep it
closed on your desktop until a message arrives.  You can modify this
beeping and flashing behavior; see the man page for more details.

You can instruct contool to filter and ignore certain common console
messages, or act upon them.  The man page explains how to create a file of
filters in ~/.contool; the included sample.filter is how my filters are set
up.  You can modify this to suit yourself, and copy it to ~/.contool.