I wanted to tag Helsinki's Museum of Modern Art Kiasma with a link to Plazes.com.
Plazes allows people to post comments about a place. For example, I wrote about Kiasma: “This is the only place in Helsinki with decent lunch and free Wi-Fi”. (BTW Stefan and Felix, the 'delete' button doesn't work. It duplicates the comment.)
I took the Plazes URL for Kiasma and wrote it on one of the RFID stickers. The museum staff wouldn't let me attach the sticker on the wall though. I had to speak to three staff members before the PR manager let me attach it on the information board by the entrance.
There it is now, on the lower left corner of the info board: a link to a free, unlimited space to speak out your mind about Kiasma.
(For further inspiration, see Jyri's presentation about tagging and free speech).