I have just wrote a simple code for auto tagging with the help of a Automatic Keyword Generator by Ver Pangonilo.
This script automatically tags your posts.
1. it fetches content from your pligg_links database
2. loops it into the auto keyword gen
3. Cleans it up and make sure the data is not already in your tag database
4. Inserts the tags into the tag database.
Someone suggested if I was using "yahoo terms " , No I didn't use it, it uses a declared string of frequently used english terms.
I am currently reading on yahoo terms and i might adopt it, so give me a day or so, it might work better with it.
If anybody is interested in the code, do let me know. I haven't converted into a mod yet. I prefer using it externally and running a cron job daily.