On the point of AC-AC converters i have a article but this is meanth for voltage regulation (ac-ac)
Powerfactor isn't mentioned in this paper but it might bring you to idea's .http://rapidshare.com/files/236066661/ac-ac-buck.pdf
Just have a look maybe this setup can be usefull for ac-ac conversion .
From what i remember either Pressman or Marty Brown also mentioned ac generation setups in their switchmode books .
(i uploaded those last year to the ebooks section)
In itself i think the ac-ac setup from this paper is nice ,for a 100 Watt there shouldnt be to much trouble .
Good luck and be carefull .