Custom UserAgent HTTP tag

[diasf]

Hi,
Any of the good souls present here could please do a patch in which the user can be able to choose the UserAgent tag's content? Like a simple combo with a couple of options (IE/PC, iphone, etc - I know the iphone one already exists as a patch), or even a plain textbox.

Thanks
(not all sites work the same way when they recognize the "tablet".. and sometimes the pc version is more useful anyway )