I noticed the following flaw in the reputation you get on questions: when a new user (rep 1) asks a question and gets 5 downvotes and then 1 upvote he has 5 rep, but when he gets the upvote first and then the downvotes he'll have 1 rep. Shouldn't the rep you have be independent of the order of the voting?
This could be solved by allowing rep to go negative internally, but clip it to 1 when shown on the page.
By the way, I think the same problem may arise for users who meet the 200 rep daily cap: if you have 200 rep for the day, when you get downvoted first and then upvoted you'll have 200 rep, when you get upvoted first that won't be registered because of the cap, but a later downvote will be registered and you'll have less than 200. Again this can be solved by keeping a count that may go beyond 200 per day, and apply the cap only once at the end of the day.