When submitting your website to directories, make sure that the directory is credible enough that it may not affect your Google page rank. The top directories that Search Engines trust are:

• Yahoo! Directory ($299 annual recurring fee)
• DMOZ (Free, but it takes time to get listed)
• Business.com
• BOTW ($99 annual recurring fee or $249 one-time review fee)
• JoeAnt (one time fee of $39.99)
  
• GoGuides

Before submitting to a directory, make sure to evaluate its quality. Try not to list under directories that:

• requires reciprocal link
• clones DMOZ
• has zero page rank (or clones its page rank)