You actually could use delicious, with a tag for each group. If you really don't want different groups to see your other links you could use different usernames.

e.g. if your username was JustAGeek you could have any links for your friends tagged with 'friends', and the URL for those links would be http://delicious.com/justageek/friends.

For work you could have the username 'justageekwork'.

Delicious generates an RSS feed for any tag as well, just visit that URL and it gives you an RSS feed URL for that list of links.

Use the delicious firefox plugin for the one button click sharing functionality.