I take a thermarest ultralight 3/4 in summer and I can use it in a hammock or on the ground.
In the winter I also take a german issue folding foam mat an isomatte, great bit of kit for the money £5 from:
http://www.flecktarn.co.uk/productsflc.html#bivouac
Extra insulation when it goes below freezing and an incredibly good sit mat when folded. It also fits behind the back of a PLCE Bergun taking up very little room and giving extra comfort on your back.
In the winter I also take a german issue folding foam mat an isomatte, great bit of kit for the money £5 from:
http://www.flecktarn.co.uk/productsflc.html#bivouac
Extra insulation when it goes below freezing and an incredibly good sit mat when folded. It also fits behind the back of a PLCE Bergun taking up very little room and giving extra comfort on your back.