Something like this would be useful:
dmesg | grep -iC 3 "what you are looking for"
For example, if looking for your video card, you could try:
dmesg | grep -iC 3 "video"
dmesg | grep -iC 3 "graphics"
C 3 flag will print 3 lines before and after the matched string, just to give you some context on what the results are. But as @tohecz said, there are thousands of possibilities.
All depends on what you are looking for... sound, wifi, usb, serial, reader....
If you expect a usb key to appear in there, you can try grepping for
Just found this page, that contains sound advice on how to grep stuff in there:
Because of the length of the output of
dmesg, it can be convenient to
pipe its output to grep, a filter which searches for any lines that
contain the string (i.e., sequence of characters) following it. The
option can be used to tell grep to ignore the case (i.e., lower case
or upper case) of the letters in the string. For example, the
following command lists all references to
USB (universal serial bus)
devices in the kernel messages:
dmesg | grep -i usb
And the following tells dmesg to show all serial ports (which are
represented by the string tty):
dmesg | grep -i tty
The dmesg and grep combination can also be used to show how much
physical memory (i.e., RAM) is available on the system:
dmesg | grep -i memory
The following command checks to confirm that the HDD(s) is running in
DMA (direct memory access) mode:
dmesg | grep -i dma