Electrum - Lightweight Bitcoin client


Encrypted wallet: the file that contains your bitcoins is protected with a password. You are protected from thieves.
Deterministic key generation: If you lose your wallet, you can recover it from its seed. You are protected from your own mistakes.
Instant on: the client does not download the blockchain, it requests that information from a server. No delays, always up-to-date.
Transactions are signed locally: Your private keys are not shared with the server. You do not have to trust the server with your money.
Privacy: The server does not know you, it does not store user accounts. You are not tied to a particular server.
No javascript: Electrum does not download any script. A compromised server cannot send you arbitrary code and steal your bitcoins.
No single point of failure: The server code is open source, anyone can run a server.
Firewall friendly: The client does not need to open a port, it simply polls the server for updates.
Free software: Gnu GPL v3. Anyone can audit the code.
Written in Python. The code is short, and easy to review.


The project is hosted at https://gitorious.org/electrum
Installation from gitorious (Linux):

sudo easy_install ecdsa
sudo eady_install pycrypto
git clone git://gitorious.org/electrum/electrum.git
python ./electrum/client/electrum.py

Tar archive: Electrum-0.26b.tar.gz.
Zip archive: Electrum-0.26b.zip.
Windows executable (created by BTCurious): check in the forum thread
Note for Windows users: if you do not use the executable, you will need to install pygtk and pycrypto. You can find pycrypto for Windows here