I had thought about that, too, but then the NSS would just be hosting a caving slide show, consisting of many images that many people already have on the Web in slide shows. I think that's something that should be considered or pushed by someone else. Perhaps we should just have a page here in the DB or elsewhere on the NSS Web site that has links to caving slideshows. The other problem with going to the larger images is you'd really need to have them in a slideshow where whoever took them could explain what people were looking at, I think.
The random image code is very lean and mean (to make it fast) and I only wanted to have something the same size as the animated flying bat that would represent "cavers" and draw people to the list of people online. I had a static image there but that got old really fast, so I looked for a way to change the image and make the index page a little fresher.
BTW, I have messaged Josh to suggest perhaps the home page of the NSS site use the same code to alternate larger images there -- instead of the same one all the time (particularly since the one currently up isn't a good representation of a normal cave, IMO). I've seen some very creative grotto Web sites using flash to display images and I'd like to see someone incorporate that onto the NSS front page -- but that's a personal idea. Something like that would up to the IT committee, wouldn't it?