Rated 4 out of 5 stars
I suggest that you implement a few of the options available in Word 2003 for its Find tool.
---Find whole words only [VERY IMPORTANT ONE]
---Use wildcards (I assume * for multiple unknown characters and ? for an unknown single character).
---The Next and Previous buttons are already in place and are very important to keep.
For me the vital one is Find whole words only. Recently, I had to search the meaning of an abbreviation LE that appeared on web pages and I could not check quickly this single LE word on a web page because the Firefox Find tool led me instead to words that contained LE in it and they are so many that it was pointless trying to use the Firefox find tool for such a task.
Hope this remark helps you improve further this add-on. Thanks for sharing it.