So have your web site up, or even better your community site.  You have few people who visit everyday.  They write their post get involved and are stars of you community.  Then the large majority just come back when the think of it.

Slowly they disappear. 

We have a client (NOAH) who has this issue with their Community Sever site.  Community Server like most community sites provide RSS feeds for different content sections.  The web savvy add the feeds to their feed readers.  However, a large majority are not that savvy.  In comes the Google Gadget that we built, with a lot of borrowed code. 

Users can add this to their Google homepage and see updates when the want without having to go to the site directly.  Add to that Google Donate (Support NOAH) tab.  Keep them involved. 

If you would like something similar let us know and we can work with you to customize for your needs.  Or if want the source let us know and we will be happy to get for you.  If you have other ways your using Google Gadgets promote your mission please share.