Best Sharing Tool Rated 5 out of 5 stars
Every time I install Firefox, Stumbluepon is the first extension I add. The reason isn't the usual; it's not so much to discover new sites as it is to share things among family members. I see a product we could use, and I stumble it to my husband. I see a tech joke and I send it to my son. I do use it occasionally for traditional stumbling, too, but it's hands down the best tool I've found for easily sending pages to people I know. I can even send it to people who don't have Stumbleupon now that they've added stumble-to-email support.
The one criticism I have is that the stumbleupon pages themselves, the "stumble blogs" where your stumbles are collected continue to get uglier, more complicated, and less appealing. But I still gave the extension five stars because 1) you really don't ever even need to look at stumble blogs, and 2) the toolbar and the process work so flawlessly on Firefox.