I don't really consider +44 or AVA side projects. I mean when blink dissolved, those were their main bands (and arguably AVA is still the greater "labor of love" or what have you for Tom). Even if +44 only made one album, it was the only thing Mark was doing at that point. Not a side project. Boxcar Racer yes obviously though. Still an awesome record as well.
Right now I love the Trio's side projects: Dan's The Emergency Room and Matt's theHell (which coincidentally announced they're making new music today). And Heavens is one of my favorite one-off side projects. The New Amsterdams is one of those started-as-a-side-project deals too that I love. Bayonet is another great one.
Omg how could anyone forget The New Amsterdams? They definitely should have made the list, especially with Matt just recently announcing Outroduction will the last TNA album.