Two essential mixes floating around at the moment.
First up is Kode9's absolutely brilliant mix on the Sónar site. At the moment it is only streamable (is that an actual word?), but Kode9 has promised on his blog to make it available for download later on. And he'd better 'cause it is hot as hell featuring some brand new Hyperdub dubplates.
Next is Sebo K's mix for Resident Advisor, a site that has been responsable for the majority of good mixes on the net for the last year or so (Ewan Pearson, Ripperton, Alexander Robotnick). A very nice mix positioning itself somewhere between deep techno and house, with a few old hits thrown in for good measure.
As we speak the latest RA mix by up-and-coming man Efdemin has been added to the site. Listening to that one now, so do not really know whether it is recommendable.