Fairfax County maintains a big list of consignment and thrift stores.

Classic Home Consignment
5601-G General Washington Drive
Alexandria, VA
703-916-7500

Classy Consignments
7104 Brookfield Plaza
Springfield, VA
703-644-4655

Clock Tower Thrift Shop
 2860 Annandale Road
Falls Church, VA
703-237-1910

Columbia Pike Thrift Shop
4101 Columbia Pike
Arlington, VA
703-521-3110

Consigning Women Apparel
6901 Old Keene Mill Road #100
Springfield, VA
703-569-2054

Fair Oaks Hospital Thrift Shop
 9667 Lee Highway
Fairfax, VA
703-273-3519

Fort Belvoir Thrift Shop
(on Ft. Belvoir Army base)
Bldg. 238 16th Street South Post
Fort Belvoir, VA
703-360-3186

Fort Myer Thrift & Gift Shop
142 Forrest Circle
Fort Myer VA
703-527-0664

Georgia Avenue Thrift Store
6101 Georgia Avenue, NW
Washington, DC
202-291-4013

Goodwill Industries
6136-A Arlington Boulevard
Falls Church, VA

Goodwill Industries
4714 Columbia Pike
Arlington, VA

Goodwill Industries
10 S Glebe Road
Arlington, VA

Goodwill Industries
4890 Boiling Brook Parkway
Rockville, MD

Goodwill Industries
8014 Sudley Road
Manassas, VA

Goodwill Industries
619 S Frederick Avenue
Gaithersburg, MD

 Goodwill Industries
 1039 Lawrence Street, NE
Washington, DC
202-636-4233

Hidden Treasures Thrift Store
 7755 New Providence Drive
Falls Church, VA
703-207-0708

Joseph's Coat
 3022 Annandale Road
Falls Church, VA
703-538-6289

Junior League Thrift Shop
 5503 Leesburg Pike
Falls Church, VA
703-893-0258

L & N Super Thrift Store
 3112 Georgia Avenue, NW
Washington, DC
202-882-3034

 L & N Super Thrift Store
1830 14th Street, NW
Washington, DC
202-588-0020

Montgomery County Thrift Shop
7125 Wisconsin Avenue
Bethesda, MD
301-654-0063

Nami Thrift Shop
10730 Connecticut Avenue #1
Kensington, MD
301-949-5731

Orange Crate Thrift Shop
 112 N West Street
Falls Church, VA
703-533-9268

Pennywise Thrift Shop
144 Church Street NE
Vienna, VA
703-938-7062
 
Pink Elephant Thrift Shop
 6127 Backlick Road
Springfield, VA
703-451-2467

Prevention Of Blindness Society
 942 Wayne Avenue
Silver Spring, MD
301-585-0331

Salvation Army
6528 Little River Turnpike
Alexandria, VA
703-642-9270

Salvation Army
2421-A6 Centreville Road
Herndon, VA
703-713-6691

Salvation Army
7440 Sudley Road
Manassas, VA
703-369-5186

Salvation Army
14647 Jefferson Davis Highway
Woodbridge, VA
703-494-8140

Success Thrift Store
 1512 King Street
Alexandria, VA
703-739-2292

Treasure Trove (benefits INOVA Fairfax Hospital)
 7036 Columbia Pike
Annandale, VA
703-256-7715

 Treasure Trove (benefits INOVA Fairfax Hospital)
 1315 Chain Bridge Road
McLean, VA
703-356-8704

Westover Thrift Shop
 5906 Washington Boulevard
Arlington, VA
703-241-9227

Used computers; These stores usually have computers as low as around $100 (no monitor)

Computer Warehouse
Tyson's Station Shopping Center
7516 Leesburg Pike
Falls Church, VA
703-821-1400

PCRetro.Com Retail Store
5031 Garret Avenue
Beltsville, MD
301-931-6630

Market Pro Shows has good deals on computer stuff, particularly software.

 Food Co-ops:

H Street Community Market (NEW!)

Glut Food Coop
4005 34th Street
Mt. Ranier, MD
301-779-1978

The Maryland Food Collective
9827 Rhode Island Avenue
College Park, MD
301-220-1100

Bethesda Co-op
6500 Seven Locks Road
Cabin John, MD
301-320-2531

The Uncommon Market Food Co-op (now closed)
Arlington

Common Market
Frederick, MD

Takoma Park Silver Spring Co-op
8309 Grubb Road
Silver Spring, MD
301-247-2667

Takoma Park Silver Spring Co-op
201 Ethan Allen Avenue
Takoma Park, MD
301-891-2667