Here's my list of the top 25 blog directories (in no particular order!) to which you can submit your blog's URL for free. I've included a little info for each in regard to submission rules and registration to help you decide which directories are most suitable for you.
- Technorati Your blog may already be listed, but do register to "claim" your blog, add tags and more. Hugely popular!
- Yahoo Directories: Weblogs Different directories to choose from. Premium (faster) inclusion available. No registration, except to submit your name and email address.
- DMOZ.org Weblogs Submit your blog for consideration into this hugely popular directory. No registration, just email address.
- BlogCatalog Registration required; more than one blog can be submitted for each user.
- BlogFlux Registration required; features some great blogging tools and resources!
- Top100Bloggers Registration and backlink required; ranking displayed on blog.
- iblogbusiness.com Must be a business blog with at least 3 months of posts.
- Diarest.net For personal diaries, journals and weblogs. Sorted by country of origin.
- TopBlogSites Registration and backlink required.
- Blogroll.net Registration required. Ranking available.
- QuickBlogDirectory Relatively new site. No registration, but reciprocal link required.
- Blogoozle Free and paid listings available. Must be at least 3 months old with postings within the last 5 days.
- BlogDigger No registration required; submit your RSS/Atom feed for inclusion.
- Blogarama Account required; includes blogging articles
- BlogRankings Registration required.
- BlogToplist Registration and backlink required; ranking can be displayed on your blog.
- WeBlogAlot No registration required; ping with your RSS feed to be included in directory. Backlink is appreciated.
- BritBlog Free directory for UK bloggers. Registration required.
- TopBlogArea Registration required. Many different directories and ranking available.
- Blogamama Directory for Mommy Bloggers! No registration; email and backlink required.
- InternetPublicLibrary Free submission for informative blogs
- 9Rules Not exactly a blog directory, but by creating an account your blog's RSS feed can be aggregated.
- BlogsRating.com Add your URL for others to rate your blog. Registration is required.
- SportsBlogs A directory for sporting blogs
- Blogher Hugely popular directory and resource for women bloggers. Registration required and blog must be over 3 months old.
Feel free to add other useful blog directories by leaving your comments and a link below.