The real missing link is credit towards album purchase. If you have purchased 2 songs on an album and then you go to purchase the album you should get the original 1.98 subtracted from the purchase price. Likewise, if over time you purchase 10 songs from a 15 song album that cost 10 dollars you should get bonused the rest of the album for fulfilling the purchase price. (I know the math is screwy, but you get it)
What Apple Won�t Tell You: Get An iPod for $7