trello
It looks like Trello's default search goes only through cards' names and doesn't search through activities and checklists.
Is there a way to do that? Is it possible to use Google to search through all the information in the board?
If it can be done, than it would be possible to use manual tags by including tttag-name_of_a_tag anywhere. A search for tttag would give out all ofthe possible tags.
You could get this behavior right now by creating an organization and inviting everyone you want to be able to vote and comment to the organization, then creating a board within the organization and making your internal users the members of the board. Then go to board preferences and make the board visibile, votable, and commentable to organization members. It's a slight abuse of organizations, but it'll get you the behavior you want.
The side effect, right now, will be that the organization's existence, and its memberships, will be public-visible. Private orgs are in test right now (https://trello.com/card/board/private-organization-profile-option/4d5ea62fd76aa1136000000c/4e7206a8ec4fdc00003e63e7) so if the organization needs to be completely invisible to the public, you would want to wait for that.
When you click on the card go to "More Actions..."
Then Click on Copy
You can change the card description, if desired, and click Add
Best Answer
Search will NOT search anything beyond the surface of the card itself. A very unfortunate limitation indeed.