Not many teams can use a PG, albeit a great one, that doesn't shoot well. Need to have more than one strong scoring option opposite Rondo, or at least one scoring option and some shooters.
Some teams where Rondo would fit (caveat: Can't take the top stars off the team):
Houston - Harden as the creator star, Harden, Parsons, et al as shooters
Thunder - Westbrook and Durant. Great fit, actually, but how would WB do off the ball?
Kings - Team needs (more of) an infusion of non ball-dominant players.
Miami - Good fit in theory.
Now that we have some destinations, need to think up some realistic trade scenarios.
Kings also add an unprotected first. I doubt they would do a 2014, so Celtics would probably have to settle for a protected 2014 and unprotected 2015. Even then, I'm not sure Kings are close enough to contending to consider trading so much for Rondo. But Rondo, McLemore, Cousins is solid.
I'm not too familiar on details of Lin's "poison pill" contract. But I believe that if a team trades for Lin, they need to pay 15m in the last year. IF that's true, then Celtics don't do this unless they get a fully unprotected 2014 pick, and preferably one other than Houston's own (does Houston own another team's?). If Boston would owe "only" 8.9m each year for Lin, then I think Houston's pick, semi-protected, would be enough.
(Vitor Faverini and NOT Olynyk. ESPN TM wouldn't let me put in KO yet).
With how Steven Adams has been playing, and with Collison on the roster, Perk does not need to be there. In this trade, they get a defensive-minded wing (replacing Thabo) that can create even easier opportunities for WB and KD. Thunder obviously have to give up a hefty pick/assets for A) getting, by far, the best player in the deal and B) getting rid of Perk.
Alternate: Just Rondo for Perk, straight up. This option is only if Thunder don't want to get rid of Thabo. Imagine that defensive lineup! Same "pick rules" still apply.
Miami and Golden State offer nothing realistic.
Toronto is not a good fit, IMO, but they offer a variety of trade options, most centered around Lowry.