Below is only a sample of the dozens of products available, that you can use to compare features/prices. I picked products I thought were innovative or otherwise interesting, but have not tested nor can I recommend any of them.

Stands | Case - Stands | Docks | Car Holder | keyboards | Bags | Display Interfaces - Wireless Display or WiDi adapter

Stands


Some
cases (see below) double as stands 16 Terrific Tablet Stands - From Treetop Tablet Displays to iPad Tripods at TrendHunter.com

Case - Stands


iPad:
Targus VuScape Cover & Stand for iPad 2 Case $22
Apple - Smart Cover - Cover up, stand up $39
Gilsson PU Leather Multi-Angle Adjustable Stand/Carrying Case for Apple iPad $21
Speck Products | iPad Cases | Tablet Cases | Covers for iPad
Timbuk2 Kickstand Case for the iPad - Timbuk2 Bags $49 ($29 Sierra Trading Post)

Samsung Galaxy:
Samsung Galaxy Tab Cases at myincipio.com
Samsung Galaxy Tab 10.1 cases (Review) | ZDNet

Docks


These docks keep your tablet charged and synchronized.

Galaxy TabĒ 7.0 HDMI Multi-Media Dock $43
iPad 2 Dock $29
Ilive Isd291 Black Docking Station for iPod iPhone iPad $60
Philips Fidelio AS851 review | from TechRadar's expert reviews of Audio systems $300

Keyboard Dock


Walmart.com: Hipstreet iPad 2 Aluminum Hard Case with Bluetooth Keyboard and Stand $50
Kensington KeyFolio Pro Performance Keyboard Case for iPad 2 Wireless Keyboard $60
Galaxy TabĒ 10.1 Keyboard Dock $80

keyboards

Must Have iPad Accessories - Bluetooth Keyboards $40-$90
Keyboards at PC Magazine
Foldable:
Logitech 920-003544 Fold-Up Keyboard $120
Amazon.com: Matias Folding Keyboard: Electronics $40
Amazon.com: Verbatim 97537 Wireless Bluetooth Mobile Folding Keyboard for iPhone, iPod Touch, iPad, iPad2 and Other Tablets $61
Flexible:
Menotek Flexible Bluetooth Waterproof Mini Keyboard $30
Amazon.com: Flexible Bluetooth/Wireless Keyboard for Apple iPad: Computers & Accessories $30

Car Holders


Bags


Incase Field Bag (Avail. at Apple Store Jan. 2012), similar to Kensington Sling Bag
Ipad Cases | eBags.com

Cables


Samsung Galaxy Tab (Android)
The Galaxy Tabs have
1. A 30 pin multifunctional jack.
2. An 3.5-mm audio jack 
3. An micro-SD card slot
4. 1.3 MP front facing camera for video calling

  It comes with a cable for the 30 pin port with a male usb plug for
charging, syncing and accessing the SD card when connected to a computer.

HDMI adapter $40

USB adapter $20
 The USB adapter  plugs into the 30-pin port and accepts a standard usb plug.
It will read files on a flash drive, but does not have enough power to read
a hard drive (HDD) without a powered hub.
You  need a file manager app to view files on the external device.
USB Host support (and Honeycomb 3.1) is required to connect USB accessories,
so a Verizon 7" tab won't work. The 7.0 Plus with 3.1 will work.

See Samsung Galaxy Tab  HDMI, USB and SD Card Adapters

Bluetooth Accessories

There are a variety bluetooth devices to use with your tablet. Keyboards (see above), headsets, barcode scanners, auto diagnostic interfaces to your car's computer.

Bluetooth headphones allow you to listen to music or talk on the phone in tablets with phone capability.
There are

If you want to listen to music make sure the specs supoprt Advanced Audio Distribution Profile (A2DP).This profile defines how high quality audio (stereo or mono) can be streamed from one device to another over a Bluetooth connection.
The iPad may require this profile, check with Apple or the iPad forums.

Many tablets have the phone option disabled by the supplier (e.g. Verizon) so you do not need headsets with a microphone unless you are using skype, chat or something else that requires voice input.

iPad see: iPad: Using Bluetooth headsets and keyboards at apple.com
iOS: Supported Bluetooth profiles
Bluetooth Help: Using a Bluetooth headset with your computer

Some people reported problems with bluetooth headphones on iPads. Mono headsets may not work with iPads. One forum post said, "you are going to find the implementation of BT very frustrating on the iPad."

Teksoft has a variety of apps for use with bluetooth keyboards, headsets and barcode scanners.

Prices range from $20 to $120 or more.
See Bluetooth headsets

Auto Diagnostics:
Bluetooth adapters are available to plug into your cars Diagnostic Link Connector (DLC) port allowing mobile device apps to see a diagnostic codew related to the problem which caused your check engine light to come on and look at other information picked up by sensors in your car.

Display Interfaces - Wireless Displan (WIDI)

Wireless Displan (WIDI) or Mirroring devices plug into a projector or large monitor and can mirror the display of a laptop, tablet or smartphone so you can make presentations from your own device.
Bad news:

  • The Apple TV system just connects with MacBooks, iPads and iPhones.
  • Miracast and WiDi devices work with Android tablets and phones as well as recent Windows systems, but not Apple products.
  • Samsung's AllShare Cast Hub links only to the company's own Galaxy phones and tablets.
  • Chromecast works with Macs, Windows PCs, iOS and Android devices, but relies on apps rather than true mirroring for most devices.
From Brenda Bell (ACGNJ):
Needed primarily for mobile (Android) connection. I recommend the Netgear Push2TV PTV-3000 (the model I have) Amazon.com link: www.amazon.com/NETGEAR-Push2TV-Wireless-Miracast-Certified/dp/B00904JILO/

Based on the site for the following item, 'm not sure whether a USB adapter might be a better idea:
EZ Cast USB - a dongle that allows iOS, Android, Windows and Mac devices to mirror their desktops via USB connection. $29 at shopping.iezvu.com/prod?p_id=92&lang=en

The iOS connection depends on the regular iPhone/iPad charging cable, not a proprietary HDMI connector cable (see this Amazon precanned search: Amazon Search )

A couple of folk have suggested Chromecast as an alternate option. I've not worked with Chromecast (Frank does have a Chromecast device). ComputerWorld's 2014 review of mirroring devices states "Chromecast works with Macs, Windows PCs, iOS and Android devices, but relies on apps rather than true mirroring for most devices".

Mirroring-devices-let-you-present-without-wires | computerworld

Miscellaneous

Mini Dual USB Port Car Charger Adapter $3.67
Amazon.com: Cocoon GRID-IT! Organizer Case, Black (CPG7BK): Computers & Accessories $10
Styluses
Camera Lenses:
Waterproof cases

Smart Phone Accessories:
Smartphone cases
Amazon.com: Brando Flexible Mini Capsule Microphone: Cell Phones & Accessories $20
Amazon.com: Joby JM1-01WW GripTight Mount (Black): JOBY: Cell Phones & Accessories $13

Links:
Mobile phone accessories
My tablet notes
iPad:
Memory Cards
64 Innovative iPad Products - From Luxury iPad Sheaths to Entertaining Apps
Apple.com - iPad 2 - Make your iPad even better with accessories.
iPadAccessories.com
Accessories | iPad, iPhone 4, ZAGGfolio, ZAGGsmartbuds | ZAGG.com
Tablets:
Amazon.com: Touch Screen Tablet Accessories: Skins & Decals, Cases & Sleeves, Bundles, Screen Protectors
Logitech tablet accessories

last updated 6 Jan 2011