My vote goes for this, an excellent and multi use bit of kit, guitar lead in/headphones out, your playing. Fill it with mp3's play along, speed up/slow down tracks, has loads of rythyms and beats built in, choose different amp types, some basic effects and for me best of all, stick it in the middle of the room and record hours and hours of rehearsals at any number of different MP3 quality settings, to give damn good results.
http://tascam.com/product/gt-r1/
Best thing i've bought in years