I modified this Smarty plugin sometime ago to suit a CMSMS site. It just worked after dropping it in the plugins directory. The tag appeared in the plugins list and the function did as was expected.
After seeing Megabob's fantastic effort with ImageText, I thought this humble plugin may be useful too....
http://www.clipmagic.com.au/function.gradient.zip
To see it in action in a CMSMS site, visit:
http://www.greatvibrations.com.au
Please note that I only made it CMSMS compatible. If you need help with the function itself, best contact the author.
Cheers
psy