There are companies who offer paid Google Sitemaps services. This is something you could do yourself, and have more control over your website.
For static websites there are enough compliant Google Sitemap generators for you to choose from. This one is free and quite good.
While Google and Yahoo! have special services which enable the webmasters have control over their submissions, record crawling stats and have a good overview over crawling problems and other onsite problems (like dead links), MSN doesn’t have a specialized service. Yet, it cannot hurt for you to submit your sitemap using this MSN submission form.
Sitemaps are important because they’ll show the search engines bots how to crawl your web pages correctly. Submitting a Sitemap to any of the above mentioned search engines is not a warranty that your site will get indexed and it does not guarantee high search engine rankings (for a specific keyword phrase or in general) either. This is just a tool that helps the bots better understand the importance of each web page in a site, and not a magic wand.
My word of advice: don’t pay for something you could do alone by following all the steps described on each of the sites mentioned above. This service is not time consuming: the process (creating a Sitemap and submitting it to Google, Yahoo! and MSN) will take about half an hour. Is that easy.