Userbars have become one of the most widely used graphics on the web. They are used in the signature block within a forum. Normally they are used to show interests, hobbies, software preferences, and site affiliations. I often find myself creating mine to show sites I create or am an active member of.
Here are some of many examples I have created.
Talk Veteran Forum :

Nbc Heroes fan:

Specifications:
Although there are no standards about the looks or sizes of the userbars, the following are a few unwritten rules most designers stick to:
- Width = 350 pixels
- Height = 19 pixels (some designers prefer 20 pixels)
- Font = Visitor TT1 (BRK), found here
- A striped pattern at 45ยบ (lately I have noticed variations with a horizontal pattern)
- PNG format (GIF for animated bars)
Software:
Any graphics design software can be used to make these, even MS Paint. I personally use The GIMP. It is a very powerful Open Source program (that means is free). It can be found at gimp.org.
I hope you enjoy making bars, but if you need help, then come look for me at my forum.