If you're trying to avoid 'gaming the system' you're going to fail. The only way to get around that, and it still doesn't always work, is having a lot of voters.
So, you want to encourage ratings, put the number of mods rated on the users posts with their name and join date and avatar. Have occasional and random rewards (but small stuff) for people with a lot of ratings. Feature a "power rater" on the front page every now and then. Maybe a 'star' on their avatar for rating 100 addons.
And 1-5 is too small a range. 1-10 at least.
Oh, and then when you are actually *ranking* addons, only calculate it based on the votes of people who have at least x votes. Maybe only the top 10% of people or something. SO an addon might have 300 votes and average a 6.7, but only 28 of those votes were from people with a lot of ratings, and the 'weighted' average is 7.1. Display the rating as "7.1 weighted, 6.7 raw" which tells people two things
- The addon is pretty decent
- People who know think its better
I know I would be far more likely to look at an addon with a higher weighted score. A score of "5.1 weighted, 7.2 raw" is probably glitzy and pretty and useless. Or at least more likely to be than the other, right?
What do you think, sirs?