hello,
When you write a random word in mozilla is it in a text box, or are you thinking of maybe a wiki, like wikipedia, in which case you can just enter text and define it as a link (I think)…in the example below, I have cut and pasted some text from the editing tab in a wikipedia article about ‘Wormshill’. You can see for instance, if you look at the original page (http://en.wikipedia.org/wiki/Wormshill) that the following words are links; village and *Civil parishes in England|civil parish
*This is the beginning of the entry on wormshill in wikipedia linked to above… Wormshill is the first word in the entry, that is after the headings,and the first word below.
'''Wormshill''' ({{IPAc-en|w|ɜr|m|z|ˈ|h|ɪ|l}} {{respell|wurmz|HILL|'}}), historically '''Wormsell''', is a small [village]] and [Civil parishes in England|civil parish]] within the [Borough of Maidstone]], [Kent]], England. The parish is approximately {{convert|7|mi|0}} south of [The Swale]] and {{convert|8|mi|0}} east of [Maidstone]].
These words are surrounded by and ]] to define them as links, but they only work on wikipedia’s site specifically or other sites running media wiki in general, because there the server (I think) knows what they stand for. Otherwise with HTML you have to define links, as was previously mentioned…Although it sounds as though you are talking about a WYSIWYG editor, which I think is what is on wikipedia, or rather what one uses to edit wikipedia.
By the way, the addon you mentioned is designed to allow one to highlight and open a word on a page as though it were a link but that will only work if it is in the proper format, that is URI, so that the web browser knows where to go and how to do it. Which is kind of the other half of typing a link into any web page. https://addons.mozilla.org/en-US/firefox/addon/text-link/ . Also, in seamonkey and many browsers that I am aware of highlighting and right clicking will give you the option to search for the word in you default search provider/engine without any addon.
And finally the first thing that poped into my head when I read the question was Tomboy, in which you can put ‘post it’s’ on your desktop and add html links fairly easily, also they will link to one another.
have a good day,
a5’