The google sitemap is a great idea. For Yahoo and MSN,
try adding an RSS feed to the “My Yahoo” section on Yahoo. It will most likely get the Yahoo bot to crawl your pages at least once a day. MSN has an add RSS feed feature, too, but I haven’t gotten dramatic results with it.
To learn more about creating an RSS feed, go to forums.seochat.com and do a search on it. There’s plenty of info on it.