Try this to get you going;
http://www.domaining.in/ 5
http://www.freewebsitedirectory.com/ 5
http://www.illumirate.com/ 5
http://www.info-listings.com/ 5
http://www.publimix.net/ 5
http://searchsight.com/Directory.htm 5
The number after each is the page rank.
I wouldn't go mad with it - otherwise it is spamming and you can get penalised. Just submit your sites to each and then let it go.
Am not an seo expert, so not sure how often you should do this. I just do them once or twice a year. Anyone else know more about frequency?