yes i totally agree on the Cabaret Voltaire front, i like how in their early material they used other group's songs like any other snippets of pop culture history to be filtered and distorted, like news broadcasts or political speeches. their track 'She Loved You' (sic) on
1974-76 stretches the idea of a cover version; is reciting the Beatles lyrics in a totally altered context (as a sinister whisper over a slow-motion electro-drone) a cover, or a sort of sampling (and indeed the track is credited to Kirk/Mallinder/Watson), or something inbetween?
my favourite cover version: The Shamen 'Purple Haze'; deconstructing the 'rock' element (Hendrix's original guitar sampled and attached to programmed beats, vocals spoken rather than sung, in a deadpan, broad scots accent), but still a knowingly 'psychedelic' selection. they even released an instrumental remix of it as one of their own tracks under the title 'PH1'.
and thinking of The Shamen reminds me, there are also adaptations of poems, such as their version of Mark Twain's 'War Prayer', the Blue Aeroplanes doing Sylvia Plath's 'The Applicant' (both great tracks i think, although such 'high' cultual borrowings maybe risk pretentiousness), then there is The Fall's 'Jerusalem'... these are also interesting 'cover versions'. The Fall, of course, do a whole sideline in
obscure covers.