MyEtherWallet is an Open Source, Client-Side Javascript tool that allows you to:

It also comes in a Chrome Extension that allows you to save your wallets in your browser for easier access.

The Basics

For an in-depth How-To and FAQ's, please refer to the Help Page

DAO-Specific FAQ's

Will I be able to vote on proposals?

Yes, starting on May 28th, when the creation period ends, The DAO tab will be replaces with an interface to send DAO Tokens and vote on proposals

Why did my transaction not go through?

You most likely ran out of gas. Please use The DAO Tab, or manually increase the gas to 85000 via the "Advanced" button under Send Transaction.

Will I be able to Split the DAO via MyEtherWallet?

Not at this time. However, in the future MyEtherWallet will have a way to interact with any contract via a provided JSON Interface (like Mist). 

I don't think my balance is right....

http://etherscan.io/ is a lovely blockchain explorer that will show all your ETH and Token balances, as well as any errors in your transactions. First step is to check you address there.

You didn't answer my question!

Check the help page or reach out via email at myetherwallet@gmail.com.

Where?

Who?