Janine Popick lists 29 ways to collect email addresses on the Vertical Response blog. Here are the first 10:
- Put an offer on the back of your business cards to get people to sign up for your newsletter.
- Tradeshows – Bring a clipboard or sign-up book with you to tradeshows and ask for permission to send email to those who sign up.
- Include a newsletter sign-up link in your signature of all of your emails.
- Send an opt-in email to your address book asking them to join your list.
- Join your local chamber of commerce, email the member list (if it's opt-in) about your services with a link to sign up to your newsletter.
- Host your own event – Art galleries, software companies (one here has a party every quarter and invites the neighboring businesses), retail shops, consultants (lunch & learn) can all host an event and request attendees to sign up.
- Offer a birthday club where you give something special to people who sign up.
- Incentivize your employees – Give them $ for collecting VALID email addresses.
- Giving something for free like a PDF? Make visitors sign up to your opt-in form before you let them download it.
- Referrals – Ask you customers to refer you, and in exchange you'll give them a discount.
Be Relevant 
Nice article but Why not to use an email extractor software?
On a similar note, check out the rather controversial and helpful post by Tyler Garns on the Death of the Free Report.
Free reports are not the only way to get leads, and using a download solely as a way to generate leads isn’t the most preferred way to generate qualified leads. 😉
~Joseph