Because there really is a fantastic broader range of reading material out there, and I can tell you from experience that it's very fun to read.
Des has already recommended Nesh's spin-off, so I'll repeat here that it is fantastic but won't include a link. Phobos' work I...haven't read much of, but what little I've read was pretty great. In fact, I just reread this one (NSFW, it's a Bad Slash mission), and it's hilarious. So yes--seconding those.
As for some new recs: Araeph's Mara and Isaiah are fantastic, in the Department of Technical Errors, and are probably among the first spin-offs I ever read. Looking at the wiki page, they seem to have done only (or mainly, if my eyes just skipped over something) LotR and Pirates of the Caribbean missions, but...honestly, even if those aren't your fandoms, I'd still recommend them. They're amazing.
Another two, which have crossed over with each other a lot, are the spin-offs of Miah and Caddy-shack. This links to Agent Miah's page, and this to Maria Nightingale's. I wish I could link to Cadmar's page, since he ended up being my favorite of the lot, but it's currently blank for some weird reason that I can't figure out. The pages of Agents Cali (partnered with Miah) and Maria should link to most of the stories with him, though. Miah's agents seem to be DMS, while Caddy-shack's are Floaters; and between the two of them, they've covered a lot of canons, about half of which I'm not familiar with. The characters really ended up shining; I definitely recommend these two, and, er, hope that I didn't do it too confusingly. (Also, what's up with Cadmar's page?)
Who else...hS' Driftwood series is pretty great, and can be found in the 'Partnered with Kaitlyn' section of Agent Selene's page.
Lily Winterwood's Christianne and Eledhwen are fantastic as well.
And, certainly not least, EileenAlphabet's duo of Mittens and the RMC (Radioactive Moss Creature) is hilarious.
And one more--Fish Custard's Evie and the Fisherman are hands-down amazing. Especially Mission #6.
Beyond that--because, really, I could easily continue for several pages at this rate--I suggest checking out the Complete List of PPC Fiction. It's not always up-to-date (looking at myself here, actually), but it's pretty extensive and goes by department. It's a fantastic place to start looking.
And beyond that, try using the Random Page function on the wiki (or else ask other people for recs). You'll quite likely find something new and interesting just by doing that.
Happy reading!
~DF
PS: No, seriously, what's up with Cadmar's page? Why is it blank except for the title? Does anyone know?