Artifakt Digital

The artifakt Hashtag Plugin allows you to easily and quickly make keywords 
searchable across your website, in the same way it does on other websites where 
hashtags are used. Just adding the # symbol in front of a word or phrase makes 
it a link to the archive page of that hashtag.
Originally this plugin simply created links to a search results page for the 
hashtags, and that worked well but we got to thinking about SEO and how it 
would be nice to index the hashtags on your site. So we created a custom taxonomy 
“Hashtags” (duh) so now you have some options on how you display the archive 
pages and the SEO meta for the pages (if you are so inclinded). You could even 
create a tag cloud of all your hashtags using WordPress’ tag cloud widget.
We are leaving all the customizing of the archive pages and SEO work up to you 
and your theme but your options are much more plentyful since version 2.0
Have fun! And as always, please let us know if there are any issues or 
features you’d like to see.

The artifakt Hashtag Plugin

This plugin makes #hashtagged keywords searchable across your website.

rich! @ etiviti

rich

** IMPORTANT ** 
This plugin has been updated for BuddyPress 1.5.1
This plugin will convert #hashtags references to a link (activity search page) posted to the activity stream
Works on the same filters as the @atusername mention filter (see Extra Configuration if you want to enable this on blog/comments activity) – this will convert anything with a leading #
Warning: This plugin converts #hashtags prior to database insert/update. Uninstalling this plugin will not remove #hashtags links from the activity content.
Please note: accepted pattern is: <code>[#]([_0-9a-zA-Z-]+)</code> – all linked hashtags will have a css a.hashtag – currently does not support unicode.
<h4>Also works with</h4>
<ul>
<li>BuddyPress Edit Activity Stream plugin 0.3.0 or greater</li>
<li>BuddyPress Activity Stream Ajax Notifier plugin</li>
</ul>
<h4>Related Links:</h4>
<ul>
<li><a href="http://etivite.com" title="Plugin Demo Site" rel="nofollow ugc">Author’s Site</a></li>
<li><a href="http://etivite.com/wordpress-plugins/buddypress-activity-stream-hashtags/" rel="nofollow ugc">BuddyPress Activity Stream Hashtags – About Page</a></li>
<li><a href="http://etivite.com/api-hooks/" rel="nofollow ugc">BuddyPress and bbPress Developer Hook and Filter API Reference</a></li>
</ul>
<h3>Extra Configuration</h3>
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BuddyPress Activity Stream Hashtags

This plugin will convert #hashtags references to a link (activity search page) posted within the activity stream

The artifakt Hashtag Plugin vs BuddyPress Activity Stream Hashtags