The Yahoo! Portal
Yahoo! is noted world-wide with her email platform provision. Yahoo! however is the second largest search engine, estimated by experts to control 20-40%, of search traffic. To submit to Yahoo! this is the place to go .
Microsoft Network (MSN)
MSN is the third largest search engine with estimated influence of 10-30% of the search market. To submit your site or blog the go to this site.
Of the three giants, I like MSN a lot, because, it is always the first to index your site or blog, in a matter of few days- (3-7days). It is always the first to send trickles of visitor traffic to your site or blog, even if your blog is a few days old, without any rank or authority in the blogosphere.
While Google is liberal, and would still send you traffic within the first 4 weeks of submission, Yahoo! is more conservative, as it takes quite a long time (2months+), before indexing and sending you organic visitor traffic.
Since, between the three of them, they control 90% of organic search traffic, I prefer to concentrate on them. I must also confess, at this point that I have anonymously ran blogs that I never cared to submit to search engines, but because I had original content in a niche that is less competitive (long tail), but prosperous, I succeeded in driving heavy traffic to those blog in a reasonably short period, and it was a successful experiment.