Janine Popick lists 29 ways to collect email addresses [2] on the Vertical Response blog. Here are a few suggestions:
Some other suggestions for increasing your email list ...
Links:
[1] http://www.emailinstitute.com/b2b-email-marketing
[2] http://blog.verticalresponse.com/verticalresponse_blog/2009/09/change-up-your-newsletter-get-more-clicks.html
[3] http://www.emailinstitute.com/best-practices/email-marketing
[4] http://www.emailinstitute.com/best-practices/email-acquisition