Flickr

• Allsizes+ – Now with nag screen galore, but still very nice to snatch bigger resolution pictures.
• Cross recommendations – This really makes browsing random pictures on flickr much more interesting.

Last.fm

• Chart changes – See which tracks goes up and down in the most played tracks of yours.
• Aaverage plays on artist pages
• Lyrics – My favorite for last.fm, adds lyrics to the track pages.
• Normalised charts – Show charts by amount of play in time instead of number of plays. Good for artists like Opeth with long songs
• Top tracks on artist pages

IMDB

• imdb runtime fix – Show runtime in a sane way instead of in minutes only
• Enlarge actor images – on hover. Not really that useful, but the pictures are small.

Google/Gmail

• Block unwanted results – like the damn Experts Exchange described here
• Replace http with https – for better security