Cels Forum

I personally recommend--

All the prominent Miyazaki ones (have not seen others...)--
   -Nausicaa of the Valley of the Wind
   -Laputa
   -Kiki's Delivery Service
   -Tonari no Totoro
   -Porco Rosso
   -Grave of the Fireflies (but your heart may die sad watching this one)
   -Mononoke Hime

These are must sees :)

and then, of course, i recommend my favorite one right now--Cowboy Bebop !^^