Update: 2017-01-07 LightWallet is no longer being maintained, and is expected to stop working after the upcoming hardfork enabling RingCT. Please use the official GUI for now (which also works with a remote node), or wait for another third party GUI by Jaxx or someone else to be released soon.
This is a GUI frontend that runs on top of simplewallet (in RPC mode). It is designed to work with a remote bitmonerod node by default, so that it can function as a lightweight wallet for most users. By default it uses Atrides open node at http://node.moneroworld.com:18081, but you can change the node it uses to a local node during setup or at any launch; to use a local bitmonerod instance set it as http://localhost:18081.
This program is an alpha version, and although I don't think there is really any way to screw up your wallet, please exercise some modicum of caution.
Windows, Linux, and Mac
The requirements for running the program using the jar file release is a java virtual machine installed v1.7+, and monero-wallet-cli v0.10+ in the same directory. If you also want to run a local daemon you'll monerod.exe/monerod binary. The wallet and daemon files can be downloaded here: https://github.com/monero-project/bitmonero/releases
If you're using the binary LightWallet.exe, you still need to have monero-wallet-cli.exe in the same directory.
It should be OK to launch the program with an instance of monerod and/or monero-wallet-cli running.
On the initial run, it will prompt you to create a new wallet or to import one by typing/copying in the path of the keys file or importing a 25 word mnemonic seed. This will create several files in the same directory as LightWallet and monero-wallet-cli, including lightwallet.conf. If you ever want to create or import a new wallet, simply delete lightwallet.conf.
If you manage to crash the program, you will probably get an instance of monero-wallet-cli(.exe) hanging around, so to get rid of it you will need to go into the task manager processes tab and end the monero-wallet-cli process on windows, "ps -A | grep monero-wallet-cli" to get PID and then "kill PID" or "killall monero-wallet-cli" on linux, or restart your computer.
Transaction history has been disabled for the time being. If you want to parse your tx history check monero-wallet-cli.log in the same directory.