Modern Warfare 2 ping counter?

In C:\Program Files (x86)\Steam\steamapps\common\call of duty modern warfare 2\players there is a file called config_mp.cfg. Open it with Notepad/Wordpad. There are two values you must tweak, namely cg_ScoresPing_Interval and cg_ScoresPing_MaxBars. You have some discretion with the former; the latter should be set to 10. I use the following:

seta cg_ScoresPing_Interval "30"
seta cg_ScoresPing_MaxBars "10"

This is how it works. Where the number of bars shown is >1, the ping lies in the following range:

(maxbars-shownbars)*interval to (maxbars-shownbars+1)*interval-1

For an interval of 30, this means:

• One bar: >270 ms
• Five bars: 150-179 ms
• Nine bars: 30-59 ms
• Ten bars: 0-29 ms

Knowing this, you may want to assign cg_ScoresPing_Interval a lower value.

There are also tools available that purportedly unlock the hidden developer console, with which you can enable a numeric ping display. Personally I wouldn't trust programs of this nature because of the small risk that they may be malicious or result in a VAC ban. With that said, you can read about one here.