Since there seems to be even more confusion than I thought, I will try and provide some more information concerning the badges on StackOverflow:
- Autobiographer - Fill out your user profile. (only awrded once)
- Beta - Be a member of the site's beta period (only awarded once)
- Citizen Patrol - Flag you first post (only awarded once)
- Civic Duty - Cast any combination of 300 up and down votes. (only awarded once)
- Cleanup - First rollback of a question or answer. (only awarded once)
- Commentator - Left 10 comments on questions and answers (only awarded once)
- Critic - Awarded first time you cast a down vote (only awarded once)
- Disciplined - Deleted your own post that had a score of at least +3 (awarded multiple times)
- Editor - First edit to a question or answer (only awarded once)
- Enlightened - You are the first to answer a question. Your answer is accepted. Your answer scores at least +10. This can be awarded multiple times.
- Woot!/Enthusiast - Visited the site for 30 days straight (only awarded once I believe)
- Famous Question - Asked a question with 10,000 views (can be awarded multiple times)
- Fanatic - Visit the site for 100 straight days (only awarded once I believe)
- Favorite Question - Your question is favorited by 25 people (can be awarded multiple times)
- Generalist - Active in many different tags (awarded once, but not implemented at this time)
- Good Answer - Answer voted up 25 times (can be awarded multiple times)
- Good Question - Question voted up 25 times (can be awarded multiple times)
- Great Answer - Answer voted up 100 times (can be awarded multiple times)
- Great Question - Question voted up 100 times (can be awarded multiple times)
- Guru - Accepted Answer and Score of at least +40 (can be awarded multiple times)
- Necromancer - Answer a question more than 60 days after it's posting and score at least +5 (can be awarded multiple times)
- Nice Answer - Answer voted up 10 times (can be awarded multiple times)
- Nice Question - Question voted up 10 times (can be awarded multiple times)
- Notable Question - Question viewed 2,500 times (can be awarded multiple times)
- Organizer - Awarded upon the first time you retag a question (awarded only once)
- Peer Pressure - Deleted your own post after it scored at least -3 (can be awarded multiple times)
- Popular Question - Question viewed 1,000 times (can be awarded multiple times)
- Populist - Your answer has 2x the score as the accepted answer. Accepted answer must be at least +10 (can be awarded multiple times)
- Scholar - Awarded the first time you accept an answer on a question you post (awarded only once)
- Self-Learner - Accepted your own answer and scored at least +3 (can be awarded multiple times)
- Stellar Question - Question favorited by 100 users (can be awarded multiple times)
- Strunk & White - Awarded after you edit 100 questions or answers (awarded only once)
- Student - Awarded after asking a question with a single up vote (awarded only once)
- Supporter - Awarded after casting your first up vote (awarded only once)
- Taxonomist - Created a tag that is used on 50 questions (can be awarded multiple times)
- Teacher - Awarded after receiving your first up vote on an answer (awarded only once)
- Tumbleweed - Ask a question that gets no comments, no answers, and low views over the course of a week (can be awarded multiple times)
- Yearling - be a member of the site for a year (awarded only once)