Know that your email address may be traded, sold, copied and given out to untold thousands of direct email marketers from now on. Check for a privacy policy to verify the integrity of the service. What they don't want you to know is where your domain is being sent to. Try to find them on the Internet. Note how many don't exist, or the site was moved to a new domain.
Directories require forms.
If the service doesn't stop to let you fill out the form, choose a category and write your own description, you've probably been scammed. Do your research. Most have cleaned up their acts, but I remember when some of these freebie services sent your URL to personal pages and websites that had search boxes on them - anything to make the list run into the thousands. There ARE good ones. Some lesser known startup engines need the data, and these services can help provide that.