user61: Apart from the official client found at the bitcoin.org site what is the list of alternative bitcoin clients? And what OS do they work on?

user217: LoveBitcoins.org has a list of clients for various platforms.

user81: There is a current list of clients here
http://en.bitcoin.it/wiki/Category:Clients
There is development discussion around alternative clients here
http://bitcointalk.org/index.php?board=37.0
Currently the "Official Client" (more specifically, the Satoshi client) is the most widely used and has implementations that run on Windows, OS X, and Linux. However, multiple alternative clients have been developed, including ones that run on Android, and this is currently a high priority for the bitcoin community.
The current most popular alternative clients are BitcoinJ, written in java
http://code.google.com/p/bitcoinj/
and BitDroid, which runs on Android
https://github.com/cdecker/BitDroid-Network

61: <p>Apart from the official client found at the <a href="http://www.bitcoin.org/">bitcoin.org</a> site what is the list of alternative bitcoin clients? And what OS do they work on?</p>
 217: <p><a href="http://lovebitcoins.org" rel="nofollow">LoveBitcoins.org</a> has a <a href="http://lovebitcoins.org/getStarted.html" rel="nofollow">list of clients</a> for various platforms.</p>
 81: <p>There is a current list of clients here
<a href="http://en.bitcoin.it/wiki/Category:Clients">http://en.bitcoin.it/wiki/Category:Clients</a></p>

<p>There is development discussion around alternative clients here
<a href="http://bitcointalk.org/index.php?board=37.0">http://bitcointalk.org/index.php?board=37.0</a></p>

<p>Currently the "Official Client" (more specifically, the Satoshi client) is the most widely used and has implementations that run on Windows, OS X, and Linux. However, multiple alternative clients have been developed, including ones that run on Android, and this is currently a high priority for the bitcoin community.</p>

<p>The current most popular alternative clients are BitcoinJ, written in java
<a href="http://code.google.com/p/bitcoinj/">http://code.google.com/p/bitcoinj/</a></p>

<p>and BitDroid, which runs on Android
<a href="https://github.com/cdecker/BitDroid-Network">https://github.com/cdecker/BitDroid-Network</a></p>
