Also, Spidersilk Armour makes great defences against flying creatures (perhaps for a sideboard), but with the Skullclamp engine, may net you 4 cards for 2 mana (as opposed to a mere 2 cards for 1 mana).
In my testing with skullclamp you really want to have your creatures x/1 unless you have somehow managed to draw double clamp (at wich point you should already be winning) in most cases you don't want to cast spidersilk armor and being able to block fliers is not that important...there are two creatures with flying you want to block (angel and morphling) why sideboard for that...
