bertstein, Blacklisted by who? If you mean the RBL, just go to the and see. Your question is generic. Their are lots of blacklists.
Now there are lots of means of spamming a domain and getting blacklisted. Do you mean email spamming or SE spamming? If you mean SE spamming, no there is not a good way to tell. If you mean email spamming see the comment above.
dvduval, Your domain is most likely on a blacklist if you can't send an email to your friend. Contact the ISP and ask what blacklist and how you clear yourself. You should also check and make sure your server is not running an open relay.