First on our sharing list: the ability to embed an automatically updating list of your NetNewsWire / NewsGator subscriptions into your website or blog. To enable this, simply sign into your NewsGator account (if you're using NetNewsWire 2.1.x or 3.x I believe you automatically get at least a 1-year NewsGator subscription) and go to Settings > Edit Locations. Assuming you have syncing with NewsGator enabled, you should see at least one location related to your NetNewsWire feeds which should have a 'Blogroll' option listed. Clicking on that will give you all the options you need to embed a small snippet of code in your site to create a list of the subscriptions you want to share publicly.
There is another way to share your NetNewsWire subscriptions in a handy-dandy file format, easy for friends, family and visitors to download and import into just about any newsreader they use, including NetNewsWire, Google Reader and even Vienna (this is technically referred to as an OPML file, with the extension .OPML). NetNewsWire offers a File > Export Subscriptions command, but there are a few options involved and this isn't very automation-friendly. If you want to make your subscriptions available to, for example, website visitors or simply back them up on a regular basis, I put together two very basic, two-step Automator apps (packaged as zip files) that can work fine on their own or easily be incorporated into larger workflows.