Boot Logo Manager TO use this app you have to be Rooted with Busy Box. For .99 you can choose from over 280 boot logos and switch to any animation in that list with just one click! You can also set it to pick one from the list at random. The downside to this app is that it only works on specific devices, so check if yours is included in the description before downloading.

Boot Screen Changer (Root) Your phone has to be Rooted to get this app. It costs $1.99 and has a list of community-built boot animations that you can choose from.

Silent Boot This app is a great, simple way to disable any sounds your phone makes on startup. That way you can clandestinely reboot your phone if necessary (though it does not remove sounds that may occur on shutdown).

Boot Animation Changer This app works on any rooted phone with android 2.0 or above (excepting the devices listed in the ad description). It has a nice list of animations.

Boot Animations Installer If your phone meets the specs laid out in the description this app gives you access to over 150 quality boot animations.