Can putty beep when tailing a log file?

will this work?:

tail -f /var/log/messages  | sed 's/^/\a/'

MultiTail has an option to do that:

--beep-interval x
Let the terminal beep for every x-th line processed. Press 'i' in the main menu to see how many times it beeped.

This answer is slightly off to the side of your question but that's as much as I can help.

First I don't know of a simple way for tail or putty to alert you when data gets moving.

Second you need to enable beeps in Putty: check the option to pass on any bell call from the terminal session (check your settings -> terminal -> Bell). You may want to select a wav file there (or select 'flash the screen' for testing purposes).

Test it by typing control-G in the putty terminal window. So now you should have a bell that works.

Lastly, one option might be to pipe your tail to some script that checks the time for each line input (awk, perl or ruby come to mind, though I'm sure the shell would do just as well) and output a \x07 to /dev/stderr if the time difference between two consecutive outputs is greater than a given number of seconds.

For example:

(yourscript) | awk '{pt=t; t=systime(); if ((t-pt)>10) {printf "\x07" > "/dev/stderr"}; print}'

e.g.

(echo a; sleep 4; echo b; sleep 9; echo c; sleep 12; echo d; sleep 8; echo e) | awk '{pt=t; t=systime(); if ((t-pt)>10) {printf "\x07" > "/dev/stderr"}; print}'

Change 10 in the awk script to the amount of seconds you want to wait for data before beeping the terminal.