In my job, I see many firms' newsletters and firm's Web sites. There are some very good ones. The best ones show a continued effort to make them attractive and easy to read. The information is usually presented so the user can quickly get to what interests them. I particularly like those firms that list useful links in their newsletters or on their sites, and briefly describe why the sites are useful.
Another I like is
Listing useful Web sites in a newsletter and on the firm's Web site encourages use of both. Many recipients of the newsletters will probably check for those "useful sites" listings when they get the newsletter. A listing of useful sites on a firm's Web site will similarly encourage repeat visits. The links are easy to find and this information is easily maintainable on the site. You just periodically check if the hyperlink works, and if the description is still accurate. An additional benefit is such a firm is also publicizing how technologically savvy it is.