If you’re not a graphic designer, I suggest making friends with one. Graphic designers are lovely people to know, and even lovlier people when they owe you favors, so be nice to them!
If you are a graphic designer or would like to try your hand at being one, I think having a really cool banner for all your forum posting is an awesome promotional tool. You can even use it to append to your email in your signature. Here’s a tutorial on how to make an animated banner with Adobe Photoshop and Adobe ImageReady: Step by step guide to animate a banner which has been created in Adobe Photoshop
I made these in about an hour each:
If you’re not a graphic designer, but you still want a banner, try this.