creating convenient redo

[Daneel Yaitskov]

Hi,

It's strange Emacs is such powerful environment for production of the texts.
And It has the weak backuping tools. Vim's tools is more effective.
Vim supports not only operations: the undo and the redo, and the group
of the operations for traverse of condition B-tree.
I don't need the Vim's power. I never used it, but I'd like to have 
a more convient command for redo than standard one.
May be I don't know something but only way to make the redo operation is 
take the undo function to the negative arugment. Besides, This works 
not everyware. 

M-- M-1 C-_ sometimes works, but it is cumbersomely.

I have redefined C-z as (lambda () (undo -1)) but it doesn't work.

Are there minor-modes which extends this functionality into Emacs?

Daneel Yaistkov