It is your posts bar.
If your running IE, put your mouse over the bar and it will display how many posts you have.
The higher quality posts will have you recieving Applauses from the Staff members. The more of these you recieve, the more redness you will see in
the bars. So if you see members with glowing red bars, it displays this member has recieved alot of applauses.
Moderators have yellow bars. Mods, Super Mods and Admin are all supporting yellow bars.
Sometimes you will notice a member does not have a bar, or it is black. Vagabond, Valhall, Benevolent Heretic to name three. These all have black
bars, this is due to the fact they have broken their bar with recieving too many applauses.
More posts, makes the bar longer. (4000 posts to fill it)
More Applause turns the bar red. After about 110 it turns black.
Mods have yellow bars.
lol 
saw it and had to have it lol 
