For kids, there's a place called Milk Money on
Ridgewood in Maplewood or South Orange. Just take 
Ridgewood until you see a few stores and it's on the
right. It's OK. As far as stores for adults, I have
not used it, but there is one in the same strip mall
as King's on Morris Turnpike called Double Takes
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Men's consignment:
Encore 123 Claremont Rd, Bernardsville, 908-766-7760
Maybe the Jr. League thrift store in Summit might
consign men's clothes I think they are on De Forest (I
investigated this and its only thrift not consignment)

Women's consignment:
Double Take in Short Hills (only takes designer stuff)
973-564-6464
Reniassance (on Ridgewood Rd in Maplewood)
Duet, S. Livingston Ave. Livingston 073-535-1133

Childrens:
Milk Money - Maplewood (a couple doors away from
Reniassance on Ridgewood Road)
There's a place on Morris Ave in Springfield - I can't
remember the name - it's a few doors away from
Kindermusik.
Kid's Consignment, 34 Lincoln Pl, Madison

Girl Teens:
Teenage Wasteland - - Maplewood (next to Milk Money
and Reniassance on Ridgewood Road)
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You can try the junior league of summit- I used to be
a member and knowthat they have a thrift/consignment
shop located right in downtown summit. (thrift only)
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I can't help with men's stuff, but I have been very
happy (for 15 years!) with Kids' Consignments in
Madison.  I get 50%, they (usually) take any 
season at any time, and they take sizes from infant to
teen.  For adult clothes I have been very happy with
Duet in Livingston.  I like Duet better 
than the one in Short Hills (near the framer and
Mailboxes).