I'm not sure how much free old content is online, but Ghastley's P4 stuff still is as well as Greylight's P3/4 items. There's probably quite a bit more. Some of it is fairly unique if you're looking for something specific, or may not be available free in a newer form. While much of it may be a bit dated, new rendering & material technologies etc. can probably do a lot, and if it's only needed for a background item, may do pretty much as is.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken