I've started writing the script, will probably take a few days as I don't have that much time to spare atm.
It'll take an url to a yacf page and attempt to output CSV with username then weights in date order on the same row. Very limited error checking obviously.
Next level(s) of automation would be to automatically work through all the pages of the weight reports thread, filter in (or out) users who are in (or out), generate a graph automagically using gnuplot, and even upload it to teh web automatically. Most of which will probably never happen. 
Parsing: check.
Output CSV: check.
Work through multiple (configured number) pages: check
Filtering: no
Graphing: no
Uploading: no
Do we want the other features? I can email/PM you a CSV file for now if you like.
I also could do with some way of handling errors when failing to fetch a page, as yacf is known for failing to provide the page. This will be for another day, though.
I can't add the automatic upload until a filtering mechanism is in place. I would suggest that having a specific piece of text in your weights post is the best way; this gives the user full control. Something like: graph=yes
Also, anyone who mucks about putting things like x+8 in their post won't get a graph as I detect the weight values using a fairly restrictive regexp to avoid complicating the parsing any further. Not that it's very complex, but I have to avoid things like people putting a weight in bold mucking things up.
