LagBar is a nice addon which inserts a lagbar onto your toolbar. The addon makes use of tbwin.dll by dohcan to insert the lagbar.The lagbar functions without any bugs or problems which i could see.It is very customizable, the addon provides a popups on the lagbar which holds all the options needed for customizing.

The options are simple and easy to understand, the lagbar can be made into two different types, one type is the Graph and the other is the Percentage.The percentage type gives you a flat representation of the lag filling the lagbar with the required amount of 'lag seconds', once you set the peak for the addon, it divides itself to accomodate the lagbar, for instance, setting 5 seconds would make the addon divide five one second parts, and it is filled according to the lag.The graph type works the same way, but the difference is that it gives you a graphical representation of the lagbar.I personally preferred the graphical representation.