Hitwise has published a nice Top 20 of Google domains. The main search page gets 79.98% of the hits to these properties, followed by image search (9.54%) and Gmail (5.51%). But most get less than 0.5%, and the bottom eight get 0.1% or less.
Hitwise says: "some of the latest Google offerings have yet to capture significant market share in their category (Google Finance currently ranks 39th in the Business & Finance - Business Information category, with 0.29% market share of visits to the category, Yahoo! Finance in contrast, ranks #1 in the same category with 35.6% of market share)."
