Of course I'm sure you know about the FE (fish extender for those that have never done
DCL before--there are many places on the disboards for you to find out all about what an FE group is). We enjoyed it as our "adults only" cruise when it was just DH, BFF, and I that went two years ago--can only imagine the surprises that the grands will get with it! We were originally not going to do it (since there are so many of us) but the DDs are getting excited about wanting to do it--so I guess we'll be considered IN for that.
The post card exchange is generally for those that want some sort of connection with our group but don't want to do the FE. Generally it is a post card from the person's home area (city, state, and some cases country if we get some of our out of states friends to join us) with a favorite recipe printed on the back of it. These are delivered to the staterooms, much the same as FE gifts would be (delivered into the FE pockets or clipped onto the fish outside the staterooms if not doing FE. Generally one person makes a list of all those participating (just like when someone organizes an FE group) and keeps track of all names, email addresses, cabin numbers, etc. so that they can provide a list to each participating member so the person will know in advance how many post cards to prepare before leaving home.
And for those of you that this is a first DCL cruise, be sure to check out the door decorating (magnets) that people have graciously provided downloadable files for magnets that fit around the port holes of the different characters "ears" for decorating doors--or other magnets as well. There is also a Free Graphics site on facebook for DCL cruisers (and others) to use for PERSONAL use ONLY--not for sale in anyway, but can be used to make t-shirts, stickers, magnets, and so many more imaginative things for your own group.
Hope this bit of info helps.