My personal dream is to have sex in a balloon, so i guess i would rent one and have a good time.
Hell, it could even bear Epass banner for a publicity!
Another idea is to invest money into something socially useful. For example, i could run a small local advertising campaign to get people to donate money or blood, or maybe just call their friends or parents they haven't talked to for a long time.
Or buy toys and books and send them to an orphanage.