next_post with pretty permalinks?

I’ve been looking at the source code of the various post navigation functions available. It looks to me like they’re simply not going to work in archives or with pretty permalinks.

A single post display is apparently not paged, so the functions return nothing. Index.php is, but mod_rewrite throws the URL on the floor and returns either 404 or teh most recent post.

I think I know how to write a plugin that will get me the next/previous post in chronological order from any post in the blog. There are threads in the forums that show I’m not the first to want this, but I can’t find such a plugin.

Is there one? Am I missing an easy setting?

Thanks,

Frank