UPDATED INFO (6/2014):
These Bitcoin keychains are brass-plated and have a 1-3/8" diameter. They are very substantial!
(We've also created a silver-plated Litecoin keychain, more info at http://Lkeychain.com)
These Bitcoin Keychains are now sold online here:
From USA, using BTC: http://cryptoanarchy.com/store/index.php?route=product/product&product_id=131
From EU, using BTC: http://btctrinkets.com/presta2/index.php?id_product=23&controller=product
From USA, using several cryptocurrencies: http://www.cryptomemorabilia.com/product/bitcoin-keychain-by-bkeychain/
From USA, using Fiat (Amazon Prime Eligible): http://www.amazon.com/gp/product/B00DJWEVHE?ie=UTF8&camp=213733&creative=393177&creativeASIN=B00DJWEVHE&linkCode=shr&tag=papercl-20
More info at http://Bkeychain.com.
If you're interested in a Bitcoin Keychain, but want to see other options, please see our friends' keychains:
http://bitcoinkeychains.com
http://btctrinkets.com/presta2/index.php?id_product=9&controller=product
And we're working on custom keychains engraved with a QR code:
https://bitcointalk.org/index.php?topic=656357
Here are a few links showing our keychains used on popular sites
http://www.pbs.org/newshour/rundown/2013/10/a-bitcoin-evangelist-on-the-virtues-of-cryptocurrency.html
http://www.inc.com/eric-markowitz/a-bitcoin-lawsuit-shakes-the-industry.html
http://www.washingtonpost.com/blogs/the-switch/wp/2013/10/02/7-revealing-numbers-about-silk-road-the-internets-darkest-drug-market/
http://www.coindesk.com/information/how-do-bitcoin-transactions-work/
http://finance.yahoo.com/news/chinas-google-now-accepting-bitcoin-182100345.html
http://www.businessinsider.com/reaction-to-texas-judge-bitcoin-ruling-2013-8
http://www.bostonmagazine.com/news/blog/2013/11/04/bitcoin-jeremy-allaire-circle-boston-university
http://motherboard.vice.com/blog/what-do-the-latest-nsa-leaks-mean-for-bitcoin
http://pandodaily.com/2013/10/25/bitcoin-down-10-as-fbi-announces-seizure-of-another-28-5m-from-silk-roads-founder
http://www.dailydot.com/news/biggest-bitcoin-win-gambling-history-nakowa/
http://www.itworld.com/security/370750/bitcoin-offers-privacy-long-you-dont-cash-out-or-spend-it
http://rt.com/usa/bitcoin-washington-dc-foundation-008/
http://readwrite.com/2013/10/23/i-bought-bitcoin-in-person-and-heres-what-happened
http://singularityhub.com/2013/09/11/bitcoins-big-year-attracts-regulators-in-the-us-sparks-ipos-in-china/
http://paymentweek.com/making-rent-with-bitcoins-and-rentalutions/
http://www.mobile.pro/index.php/bitcoin-drops-15-percent-fbi-silk-road/
http://www.itproportal.com/2013/10/08/fbi-struggling-to-crack-ross-ulbrichts-497-million-bitcoin-fortune/
http://thehackernews.com/2013/10/seized-35-million-worth-bitcoins-from.html