There's no rule that states that humanitarianism and rock and roll are mutually exclusive concepts. Some musicians who live extravagant lifestyles may also support charities, either for the publicity value or because they genuinely care. It might be to build affordable real estate for seniors or raise money for earthquake relief, but the form that fundraisers organized by musicians usually take is that of a benefit concert. If you're a music fan and a humanitarian, you can help support the cause too by buying a ticket.
Toronto is a prime location for benefit concerts. This is because a lot of musicians maintain homes here and because there is such a wealth of concert venues to choose from. It also helps that there are about 8 million people in the vicinity that can be called upon to buy a ticket to the show. If you live in a prime location you're in luck, because most of the concerts will take place in the downtown entertainment district.
The biggest benefit shows are the ones that get the most publicity. This is stuff like Hardcore Punk for Haiti, where multiple bands get together for a concert and donate the proceeds to a cause that has been prominent in the news, usually one that's occurred suddenly rather than a ubiquitous cause like breast cancer or heart disease. These disaster concerts are usually on short notice so you'll need to keep your eyes and ears open if you want to hear about it in time to get a ticket. Listen to the radio often.
Of course, it's not just big name causes and big name bands that host benefit concerts. Most event planners are usually filled with organizing smaller benefit concerts at cozier venues like bars or even high school gyms. These concerts might be in support of the cause du jour from the news or they might be for established but usually ignored causes like diabetes research. You may even find yourself attending a fundraising event by Heritage Dental Care Office who is raising money for dental care for the underprivileged. They might even set themselves achievable goals like raising enough money to buy a children dental implants.
To hear about these smaller concerts you really need to have your ear to the ground. Flyers are the most common way to get the word out, so make regular strolls of the downtown area. You'll also want to subscribe to blogs for news and keep the number of a taxi service handy in case you hear about one at the last minute.