I don't think posting ban / whitelist suggestions on specific items in this thread is useful. The purpose is to come up with a system that Valve can use to gather data for themselves. If Valve wanted the community to come up with a whitelist / blacklist for them that is a different topic.
Here are some of my thoughts.
First issue is logistics. There are over 100 weapons in the game, and a handful of set bonuses as well. We need a system that can cover all of the items while also not spending 5 minutes or more trying to set up the item list for a 15 minute match.
Second issues is troll / outlier protection. I think a majority voting system is better than any system where any one player has ban or veto power over any one item.
With these concerns in mind, here's my idea.
Each player should have his/her pick/ban list, which he/she decides offline. This makes sense because most users aren't going to change their mind for every new match, so there's no need to have the user repeat his/her choices for every single match. This saves time as well and lets matches get started faster. TF2 would need a separate menu / interface with the list of items that one can vote on, and you would go through the entire thing and select pick or ban for each. This list gets saved in your own TF2 account profile. A reasonable default setting can be debated on to be provided to people who are too lazy to go through this step and don't really want to vote.
Once a player joins a match lobby, his pick/ban list is automatically added to the pool. Once the match is ready to start, the server simply adds up everyone's pick/ban list and treats everyone as having 1 vote per item. Any item that has more bans than picks is banned, and the remainder are allowed. The final aggregated pick/ban list is displayed to every player before the match begins. This can be done very quickly to get the match going as quickly as possible without a protracted voting or debating period before every match.
EDIT: Unfortunately this system is probably much too ambitious to be easily implemented and tested in a week of IRC pugging. However people seem to like the idea in theory so hopefully Valve will at least see it and consider it.