[memobug]

You can use the built-in replacements system to do this. Just create a replacement for

_bananas_ with <a href="link to bananas">_bananas_</a>

where those underscores are spaces, and it will swap each incidence of _bananas_ with the link.

The only probs are
1) case sensitivity
2) if you edit a post containing a replacement it will insert the html (as text) on the screen and you will have to fix before reposting.

You can, of course, create your own linked replacements, like

***AMAZON*** -> <a href="http://www.amazon.com">Visit Amazon</a>

Then wherever you put ***AMAZON*** you'll get the link, with little chance someone will do it accidentally.

However, it's still subject to the limitations 1,2 above.

Regards,

Matt