There is buy one... well, one and many clones. dmoz.org would be the address. As for it being helpful, sure, if you are into categorized websites from the late nineties, littered with dead links, spam sites, and the likes of Angelfire and other free pages. Its free to suggest a site to the ODP, but that is not saying much. It's just like any other free directory. Submit your site, and head over to the next free directory. Never bother to look back, as your listing will likely never see the light of day (just like most other free directories). But again, it's free so you are getting what you pay for. On the off chance you do get a listing there is no longer supporting evidence of any substantial SEO perks (Directories have lost a LOT of value) and there is also little to no supporting evidence of any traffic (other then ODP bots and editors). And you don't even have to submit to get a listing! The suggestion pool is an optional tool that many editors do not even bother with...meaning that if you don't submit, your wait time is likely the same, and on some cases even better then submitting!
submit your site in dofollow site, it is helpful to you. here you can find huge collection of dofollow link..: http://updatetips.com/2012/04/700-dofollow-forums-list-2-0-websites-high-pr/
Dofollow forum lists are an even bigger waste of time, as all that does is encourage forums to go nofollow, and get you and your site listed as S P A M, and worse, you a spammer. DP used to be on every one of those lists, and look what happened here. And once again, Google are not a bunch of idiots, the know exactly where the sig file is on a post and they do treat it accordingly. If you disagree, you are FOOLING yourself. Most importantly, your thread is rather off topic, and as such, pushing the spam envelope as it is.