Edit 02/10/12: Upon request from mrrick, and with the inspiration of R3D X - the creator of the Lunar UI theme - here is an eleventh boot animation style.
(Looks better on device - gif previews are limited to 256 colors)
Here are ten colors of a boot animation I made for MIUI. Now all are available with and without the MIUI tag on Andy the Android - so every version is available for MIUI regardless of screen size. All ten are available as flashable zips for other ROMs as well, made to 480x800 or 320x480 - shouldn't matter for MIUI themes, but make sure to use the right screen size for flashing method. A couple have been done for 720x1280 by request and are sprinkled through the thread and available at the download page. If you want a flashable zip for another device size, do let me know.
I will upload better previews later - larger versions are at the link below for downloads.
Sorta Matrix-like, I suppose, with the scrolling binary code. These are made from 18 static images with varying layer and opacity styles in Photoshop - I think they'd look really cool with a fly in intro series, but I'm done with animation for the moment. They're packaged for MIUI in theme format - simply upload to the MIUI themes folder and choose the bootanimation from the theme chooser menu. Let me know if you'd like a different color. All three are tested and in working order 1.11.25 MIUI.
All are also available as flashable zip's for a ROM other than MIUI, all are made to 480x800 or 320x480. : I used despotovski01's Boot Animator Creator, which makes the process incredibly simple. That said, I HAVE NOT tested the flashable zips for use on other ROMS, as I am on MIUI. FLASH AT YOUR OWN PERIL. I also cannot guide you through the process, but XDA is a font of info on the subject. As usual, I HIGHLY suggest you Nandroid your shiza before flashing stuff. I left the downloads for non-MIUI versions named individually so you can verify which version you've downloaded - you should rename the file "bootanimation.zip" or whatever is appropriate to your ROM before flashing or pushing. Check your phone's thread for details.
Download the Lunar UI inspired bootanimation from the blog
Download all other versions of the bootanimations from the blog