There's no need to D/L anything. If you see a picture that you like, you can askthe owner of the site where you found it permission to use the image, and then you can either put it on your own site or, if that is allowed, link directly to the site where you found it. You can also E-mail the picture to Ziroc, who'll host it on the Ironworks (he'll give you the link).
Alternatively, you can make your own sig and find a host (the site where you link to). Sazerac is the expert in making such images, so you could follow Larry's thread. During several stages, Sazerac will show it to you and you can advise him a bit on any changes you would like. Once you approve of the image, Sazerac will put it on the Ironworks site and give you the link. You can then put it in your signature.
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The last arrow of Legolas kindled in the air as it flew,
and plunged burning into the heart of a great wolf-chieftain.
All the others fled. -J.R.R. Tolkien, The Lord of the Rings
Legolas:
Supreme Ranger-Protector of the Ironworks
Maintainer of the as of the now opened
Ranger-Protector of the Ironworks Clan Website
Recruiter of Rangers