Let's admit it. Money transfers between different bank accounts still sucks. Whether you are sharing an expense with a friend or someone is paying you for your services, you have to share your bank account number, last name on the account, zip code and some times even the routing number to let them send you money. Sharing these details through emails or IM is a security risk in itself. And it is not a good idea to share these details with people you can't trust. So, I found it very useful when I found Chase Quick Pay through which you can send or receive money only by sharing your email address.
Chase Quick Pay is a free service where you can register your checking or savings account from any US bank with an email address. Once you have registered an email address with your bank account credentials, you can start sending money to others by just entering their Chase Quick Pay email address or you can even request for a money transfer. The only catch here is that either the sender or the receiver has to have a Chase account. So, if you have a Chase account, you can send and receive money from people who are not on Chase.
If you are using this service, you don't need to give your bank account details whenever you need to send or receive money from someone. All you need to send them is the email address that you have registered with Chase Quick Pay. For more details on how to register and how to do the transfers, check these FAQs from Chase.