I recommend Electrum: http://electrum.org/
ETA: Ah, and I almost forgot... You can use the same Electrum wallet from multiple different locations simultaneously.
- No need to download the block chain. Just launch it when you want to make a transfer and it's instantly on. Even better if you enable Bitcoin URI's.
- Deterministic wallet, so just secure the seed in a safe place and you will always be able to recover the wallet even if you lose all backups.
- There are many Electrum servers to connect to, and you can switch between servers instantly. No down time.
- Even when you are offline, you will have access to your addresses.
- Portable.
- Many different GUI options. Even has a text GUI.
- Has many command-line features. Also, supports plug-ins, for instance, to help with storing labels in the cloud.
ETA: Ah, and I almost forgot... You can use the same Electrum wallet from multiple different locations simultaneously.
Second this. I love Electrum now. Used Armory/qt but it throttled my bandwidth because of its uploading. (ASDL)
That and they have an android client that syncs with the same wallet on my pc.
