How can I tell if my domain is on an email blacklist?

Try the Email Blacklist lookup tool.

One more additional piece of information related to Domain blacklist:

SBRS (SenderBase Reputation Score) - the world's largest email traffic monitoring service, with data on more than 25% of the world's email and web traffic. IronPort's SenderBase Network provides an unprecedented real-time view into security threats from around the world. With this information SenderBase can be used as a "credit reporting service" for email, providing comprehensive data that ISPs and companies can use to differentiate legitimate senders from spammers and other attackers and giving email administrators visibility into who is sending them email.

Type a domain name and check the SBRS here - http://www.senderbase.org/