I made such a list last year, using the aa.fltmaps.com map linked above, but the routes have changed since then. It also looks like I omitted some cities in UK/Ireland that weren't useful to me, but the Continent should be here. This was the list I had:
Ord-bcn,fco,cdg,lhr
lax-lhr
phl-ath,fco,bcn,mad,lis,vce,muc,cdg,fra,ams,lhr
dfw-mad,fco,cdg,fra,ams,lhr
clt-mad,fco,cdg,fra,lhr,bcn
mia-mad,bcn,mxp,cdg,lhr
jfk-mad,bcn,mxp,cdg,lhr,zrh,fco
rdu-lhr
bos-cdg
The list was very helpful for me to search int'l saver J awards & to set expertflyer alerts. OP - if you end up making a list or updating mine, it would great if you posted back here with the new list.