Windows hidden tricks?!

Hello again all .
I was researching how to get active/animated desktop backgrounds, ive done the .scr /p65552 thing and came across dreamscape etc, but its 12:40AM here in Britain and im tired so gave up for now with playing about. Also saw you can turn the transparency to clear glass but can't be bothered with that either atm.

I have been reading that Microsoft try cool little tricks and add things to the OS during development to either see if it's viable for the final release or just for fun, Also ive read that the coding for these little tricks and cool things gets left behind and isn't active so the average user never comes across them or enables them but they exist. I have read that the active background is enabled by windows in Ultimate only and vista had the function "out-of-the-box" but they replaced it with slideshow wallpapers in 7.

I was wondering if any of you lovely people out there knew any cool tricks or anything with 7? I love altering how my OS looks and performs and I thought the little bubbles bouncing round my desktop was awesome but it just froze the desktop so had to stop the task.

Ive already done:
Win7 Logon Background Changer
Still workin on animated wallpapers
Might try window glass transparency

About it, Any other cool things like that?

Thank yooooooooooou :)

Taskbar - Customize Skin

Start Menu - Customize

Common File Dialog Box - Customize Places Bar

And Ultimately

Windows 7 Forums the biggest Windows 7 help and support forum, friendly help and many Windows 7 tutorials that will help you get the most out of Microsofts new Windows 7 Operating System. - Search Results for customize windows

Thanks for the reply Tepid.
Already done those my friend, They are part of windows as standard as far as I can tell. I was more after altering things that windows doesn't normally allow as part of the standard OS, EG:
The logon background screen can't be changed as a standard function in Windows so I downloaded the software to change that, IE: Not normally allowed in the OS but is a cool feature that can be achieved.

Animated wallpapers can't be applied in the normal OS but can be achieved with software or CMD trickery.

Changing the icons pinned to the taskbar (not found out how to this yet)

I do appreciate your reply and help dude and I would skip through loads and loads of pages to find past posts on tricks that can be done in the OS but I have a 10GB download limit and if I leak into the 10-15GB band I get charged £5 more, even if it's only a few KB like 10.01GB, I normally hit 12 GB through normal use so can't risk doing too much extra incase I go over 15GB and get charged another £5 on top.