A bimonthly or monthly newsletter sent electronically or in print is very nice way of keeping in touch with your clients and subscribers and the information you supply them can be more in depth than a weekly eblast.
You can include: offers, articles, announcements, new products, related products, free upgrades, resources, social media, etc.
Your subscribers remember you and keep their memory fresh about your product or company. The newsletters bring your subscribers back to your web site once in a while to checkout your new products.
A newsletter also gives you the ability to brand yourself and your company as an expert in your field.
The more you talk about your area of expertise the more you will be recognized as an expert.
Mention new research that is going in your field, technical issues, your experiences and just as important your opinions.