There are number of great memorial fundraiser ideas. A memorial fundraiser needs to be keyed to the person it is memorializing, and must be tasteful. Ideally, It must fit the personality of the that person, while allowing for some measure of permanence. It also helps if the person has a fair bit of fame as well, or is somewhat important to the area or group of people involved. With that in mind a number of different ideas can be explored.
There are some basic ideas that most people consider. For some it can be as ostentatious as a statue of some kind, such as a bust or an art piece, while others consider something more subtle such as a bench near where the person liked to stroll, fish or even surf. Others establish a foundation in the name of the person, and fund it perpetually. Just make that the idea fits with the person, and the memorial idea should work out well. If it really fits the person well, the fundraising should go ever well, especially with the fans of the person being memorialized.