Trello Cards RSS Support

You can give the coloured labels meaningful names, which I've found really helps.

It's not entirely obvious how to do this, at first:

1. When viewing a board, click on the grey Icon just to the left of the board's name
2. Select "Preferences"
3. You'll see the labels with names like "Green (default)"
4. Click on the name of a label, a type in something meaningful, and save it.

Now, when you click on a card, and then "Labels...", the name you specified is displayed on top of the Colour swatch.

This at least saves people from having to remember the meaning you've ascribed to the different colours.

You still only get 6 colours to play with, though, and I don't believe that you can change the colours themselves.

Other nice tricks

1. If you are hovering over a card, and hit the letter L on the keyboard, it pops up the list Labels, which is rather convenient.
2. The "Filter Cards..." option at top-right allows you to use these labels for filtering.

Edit 2011-11-19

I've just noticed that there's now a shorter route to renaming labels: At the bottom of the list of labels, there is now a link to "Edit labels (sic) titles":

I've found that you can simply enter the card number (for instance '12') in the search box, like this:

When you hit enter (or click the search button), your card number 12 of the current board will be immediately opened.
Actually, that's a great experience.

Unfortunately, searching for the card in the 'Search and Filter Cards' option won't return any results, and sometimes that can be confusing.

UPDATE: it seems that 'Search and Filter Cards' option should work as well (as Bobby pointed in his answer), but for some strange reason, it isn't working for me.