Feel free to submit your own banners in this thread and I will try to keep the first post updated with them.
In other guilds I am in they have had a preferred size format so that it works better if people wish to have rotating banners. A good size seems to be 300 x 100 pixels:

So that is going to be the preferred size.
If you want to link to the guild through your banner then you need to wrap the URL around the img tags like so (removing the spaces):
[url =http://www.gaiaonline.com/forum/guilds/index.php?page_mode=4&guild_id=977][img ]http://img.photobucket.com/albums/v353/Szinriia/UKbanner1.jpg[/img]
Or use the tinyurl version to save space in your sig:
[url =http://tinyurl.com/3v6jc][img ]http://img.photobucket.com/albums/v353/Szinriia/UKbanner1.jpg[/img]
You can use tinyurl to make the image url smaller too.
To make a rotating banner such as those in my sig go to http://www.cutandpastescripts.com/ and sign up, then follow the instructions for random images. When it gives you the code the only bit you actually need to put into your Gaia signature is the URL it gives inside BBCode image tags like so: [img ]http://www.cutandpastescripts.com/cgi-bin/randomimages/randomimages.pl?username=your_username[/img]
Of course removing the space from inside the opening img bracket.
Unfortunately tinyurl doesn't work for the random image URLs. sad You can still wrap the tinyurl for the guild URL around them though.
It would probably better to save the banners you want to use and create a photobucket account to host the banners for your random banner yourself, in case someone leaves gaia and decides to remove the images from wherever they are hosting them, leaving you with broken links.
Szinriia
Vamp X edit -
H!deous
I made a really small banner for if people want to add it to their signature advertising the UK Guild. Use it as you wish:


[IMG]http://tinypic.com/2ml44w[/IMG]
H!deous made this so I thought I'd put it up here as it's a banner that can be used in a sig.
Tommy the Cat
