I tried to find a service that lets me list movies I watched for myself. May be add some my short thoughts about this movie. I couldn't find any. Please advise.
AFAIK imdb lets you create lists, you could create a list of movies you watched. I believe imdb has the biggest db out there so might be the best choice. What other features would you need?
Someone "launched" Kamuze recently on HN. No idea how good it is, I tried commenting on his post but he/she never came back. You question made me remember it so maybe it would suit you? And as I said in my comment on this post, if you read/speak french senscritique.com would do this also.
http://news.ycombinator.com/item?id=4597796
trakt.tv is a pretty good website, integrates with XBMC and VLC Media Player, I think. Also posts to your Facebook wall and Twitter page, and lets you tick off watched or owned shows/movies.