Yes, there are still a few people out there selling Apple II hardware and software. New ethernet cards, RAM cards, IDE hard drive interfaces, and Compact Flash drives have been developed since the Apple II was discontinued. Software and used hardware are also available.

a2RetroSystems - http://www.a2retrosystems.com
Home of the "Uther Apple II Ethernet Card." Currently this card is supported by the Contiki operating system, but a Marinetti driver is under development. The Apple II version of the Contiki OS can also be downloaded from the a2RetroSystems site.

Apple Auctions - http://www.t-bone.org/~apple/
Listings of Apple II related eBay auctions, by variuos categories.

B&R Computer Services - http://hometown.aol.com/rrbp/Home.html
Carries used Apple II hardware, software, and books.

Briel Computers (Vince Briel) - http://www.brielcomputers.com/
Official home of Vince Briel's "replica 1," a fully functional clone of the Apple 1 computer made with modern parts. The replica 1 comes as assembled ready for you to add your own TV/Monitor, PC keyboard and power supply or as a kit. The site also has some Apple 1 software to download.

CFFA CompactFlash / IDE Interface for Apple II Computers -
Rich is now taking orders for the 5th (and last) run of his CompactFlash/IDE interface card for the Apple II. He is also developing a CFFA1 card for the Apple1/Replica1 and Obtronix Apple1 clones of the Apple I.

Computer Circulation Center (Alltech Electronics) - http://www.allelec.com/indexa2.html
Sells the SiriusRAM 4MB and 8MB RAM cards for the IIgs, the FOCUSDrive //e and IIgs hard drive cards, and various other expansion cards for the Apple II.

Creative Soulutions - http://members.aol.com/CreatSltn/
Offers hardware, software, and repairs of Apple2, Macintosh, Laser, and Franklin computers.

Digital Dinos - http://www.digitaldinos.com/
Sells vintage computer products, including products for the Apple II.

EGO Systems - http://www.hypermall.com/ego
They're out of the Apple II business but for some reason thier web site is still up.

GarberStreet Enterprises (Bill Garber) - http://garberstreet.netfirms.com/
Home of the new RAM-4-GS, a 4-meg IIgs RAM card that uses 1-Meg SIMMS. Also sells the MicroDrive IDE hard drive controller for the Apple II, as well as used Apple II and Mac hardware. There is also some technical information and utility software on this site.

ReactiveMicro - http://www.reactivemicro.com/
Providing new solutions for the Apple II community. Thier inventory of available items keeps growing and now includes the MicroDrive IDE/CF controller, an external CF drive, the RAM-4-GS memory card, a Mockingboard clone, heavy duty power supplies, Transwarp GS cables and upgrade chips, and much, much, more.  

Intrec Software - http://www.intrec.com/proterm-a2/
Publishers of ProTERM A2, an Apple II telecom program.

Kula Software - http://www.angelfire.com/hi/kulasoft/
Mike sells a variety of Apple II software, books, and magazines related to the Apple II.

Procyon Enterprises - http://www.hypermall.com/companies/procyon/
They've left the Apple II business, but there's still some information about their products on this page.

MC Systems - http://www.isellmacs.com/
Mostly Mac, but has some Apple II parts for sale. Look in the "Apple Service Parts" categories.

RC Systems - http://www.rcsys.com/legacy.htm
RC Systems is still selling their DoubleTalk speech synthesis card for the Apple II+, //e, and IIgs.

Shareware Solutions II - http://users.foxvalley.net/~joko/
Joe Kohn's Shareware Solutions II has become the distributor for many Apple II software companies and software collections.

///SSH Systeme - http://www.wbwip.com/shh/
The German company that developed and sells the LANceGS ethernet card for the IIgs, as well as several IDE hard drive controller cards.

Software & More - http://members.aol.com/swmoretp/AP.html
A "mom & pop" store dealing in Apple II hardware and software.

Speccie's Home Page (Ewen Wannop) - http://homepage.mac.com/speccie/
Home to the Spectrum Telecommunications program for the Apple IIgs. This  comprehensive program features powerful scripting capabilities and supports TCP/IP using the Marinetti TCP/IP tool. Programs for off-line usage of the A2-Central forums (SOAR), POP3/SMTP email (SAM),  and  FTP transfers (SAFE) through Spectrum are also available on the site.

Sun Remarketing - http://www.sunrem.com/
Sells vintage Apple II and Mac hardware and parts.

Vernier Software & Technology - http://www.vernier.com/legacy/apple/
Vernier Software started out as an Apple II software company in 1981 and is still selling hardware and software for using Apple II's as lab instruments.

VintageFunWorld.com - http://www.vintagefunworld.com/items.asp?ID=1
The Apple II section of this site lists some Apple II computers, accessories, books, and software for sale.