I'm coach of a field hockey team. Every other week we visit clubs throughout the country and we meet at a specific location so we can drive together.
In the old days, I used a printed list of the team members (15) to keep track of who was present at the parking lot - so we would not forget anyone.
Of course I wanted to get rid of the paper and use my smartphone instead. This is what I did:

I created a simple list with the following structure:
playername ^date #attend #hockey

To be complete, this list is created in an excel sheet (so I only have to enter the date of the match once and excel inserts it in each row).
I then past the textlist into an email message which I send to my RTM import address.

The email I send to the team with driving instructions, address and
other details I also forward to my RTM #hockey list, with priority 1(so it appears in the list above the players). That way I have all relevant info in case someone needs the address or forget the time we play.

By using excel in the above manner, I created a full attendance list for all of our games within 15 minutes.
On my android smartphone I added an RTM Badge Widget for the #attend tag, so I can open it instantly.
Whenever someone notifies me he will not be available for a certain date, I can easily update the app - and the autosync will do the rest: each instance of my list is up to date.

This solution saves me from printing a fresh list each week, saves a lot of time keeping track of who is there

Thanks RTM for making me look smart ;-D