Is it considered appropriate to upvote my friend if I find their posts useful?
58704
How to vote on friends / colleagues ' questions (or answers)
101134
Bonus Reputations for starters, new users
80592
Sharing reputation for good comments that contribute to the quality of the answer
5255
Should the downvoters/upvoters have enough reputations on all the tags of the question/answers?
69038
Why don't people upvote questions they answer?
130008
Are Stack Overflow people *still* nice?
84130
If downvoting is so important, why does it cost reputation?
77659
Prevent upvotes for duplicates, or carry upvotes to master question
157030
Seeking feedback on downvoted question?
78594
Downvotes and close of beginner question
20950
Am I downvoting too much, or are things really that bad?
122242
Is it possible using the SE API to get a list of another user's posts that I have upvoted?
1979
Can I ask other stack overflow members to consider removing their downvote after a post has been deleted?
146776
Retrieve my comments on friend's Facebook posts
38718
Should reputation from SO carry over to Meta?
132117
Does upvoting a duplicate comment do anything?
156609
Reputation needed to upvote / downvote