Friends and family count for your first dozen at least, hopefully. After that, consider looking for online communities that need your product. For example, vbulletin forums that focus on them.
Ingratiate yourself to these communities by participating in discussions unrelated to what you're working on.
By then, you should be able to post a full thread describing what you've done, offer a few screenshots and ask if people will try it. By replying to people's questions and being friendly, you will keep the thread reasonably topped and pick up users that way.
This also works in general interest internet forums, so long as you are a reasonable participant and posting in the correct areas.
Ingratiate yourself to these communities by participating in discussions unrelated to what you're working on.
By then, you should be able to post a full thread describing what you've done, offer a few screenshots and ask if people will try it. By replying to people's questions and being friendly, you will keep the thread reasonably topped and pick up users that way.
This also works in general interest internet forums, so long as you are a reasonable participant and posting in the correct areas.