Well, Lots of folks.
On Target Technologies (still an advertiser here I think), SSK of course (look at the banner in this forum, they're usually up there), David White who is quietly making a following, Reeder as mentioned above, plus a bunch I don't remember. Talk to folks that have had them done and you'll hear good and bad about most. Some you hear less bad about, SSK in particular on this board almost never gets a black mark. OTT says they rechamber without using a reamer which sounds interesting. Do a search on this forum and you'll pull up a bunch of debates on who's better. By the way, Mike B isn't doing any rechambers for the forseeable future.
Bill