secondly this is not exactly what i'm looking for
well.. IMO it's not really clear what you are looking for

this is somewhat what i'm loocking for :
1 - http://www.qoppa.com/pas/pasindex.html
2 - http://rainbowpdf.com/productServer.php
but i want an open source version since the charity can't afford to buy licenses.
regards
so.. you want (shoud be "prefer/wish", shouldn't? ) something that process any kind of document to transform it in a pdf and that pdf should be viewable via browser withoun any installation on client pc, right?
my idea:
- install cups on SME and cups-pdf
- create a cron script that watches a folder and, each time it finds a file, print as a pdf
- create a procmail rule that do the same thing with email
- install the online viewer I linked before..
it's not a trivial thing, but should do the job..
good luck