Formerly an eWallet which needed to access and spend the funds in the wallet only the website address (URL).
This allowed the service to be used anonymously, without needing even an e-mail address. The site included a caveat warning about its use:
Instawallet does not aspire to be a Bitcoin bank and as such can only provide a medium level of security. Please do not store more than some spare change here.
Instawallet's service learned that its security was compromised and on April 3rd, 2013 closed the service. Those with funds in their Instawallet can file a claim form to get their funds.
- InstaWallet Website