Just put a link to FeedSubmitter on my site. FeedSubmitter is a web-based free service that lets you add your RSS newsfeed to 15 RSS aggregators as well as Google and Yahoo. If you are publishing your enewsletter via RSS this could help it get syndicated alot easier. Also you may want to check out Ari Paparo's "Big List of Blog Search Engines".
eINFO - a collection of articles and studies about email marketing.