BackLight provides a menu extra (really an NSStatusItem, which are fully supported in Jaguar) that allows you to turn your screensaver on and off as your desktop background. It can also change your screensaver and open the preferences. Having your screensaver on your desktop is quite a cool effect, but you should probably have a Quartz Extreme-capable machine if you want to handle the load.
STRIDER72 Very cool app, and works fine on OS 10.6.1.
Interestingly, because BackLight doesn't use the OS's "Screen Effects Engine", it can use older 32 bit screen savers that 10.6 won't run!
That is to say, I can run Marine Aquarium 2 as my desktop, but not as a screensaver. :-p
That really says something about the quality of this app that was last updated in 2003. Great great app, and I hope the original developer is still out there doing amazing things. :-) (Version 2.0)
SMALLDUCK The link seems to be broken, perhaps the developer's site is down.
A google search for 'freshly squeezed backlight' found a comment on a lifehacker.com article where user KAMON claims to have made a mirror to v2.0 of the app. The link worked for me and the app downloaded was identical to the v2.0 I already had (which I believe I got directly from freshly squeezed years ago): (Version 2.0)
If you want the RSS and Spectrum ones on your desktop check out Quartz Desktop, http://www.apple.com/downloads/macosx/icons_screensavers/ (Version 2.0)
ANONYMOUS Sadly, on Tiger, you cannot use the RSS Visualizer (or Spectrum, though I care less about that) with Backlight. *puppy dog eyes to developer* (Version 2.0)
ABSTRACTION Wonderful little toy. Absolutely hoards your cpu and requires a powerful graphics card (atleast a geforce4 mx) but hey, it's really f%@#%ing cool.
Try mixing it with Fluid for some really trippy effects. (Version 2.0)