Stars. Collect as many as you can. Stars are released from completed rows. Collect enough stars and the level will end.
Hearts. Collect hearts for extra lives, these come in very handy.. expecially for when you get stuck, by forfeiting a life, you can escape from a trap. This is vital when the blocks start to pile up.
Bombs. They are the very definition of the double edged sword. Bombs can be collected, but once released from bomb block, they start to fizz and ultimately, explode.. destroying nearby blocks and you, if you're close enough. Once collected, they can be dropped anywhere to remove unwanted blocks.
Timeout. These hourglasses can stop time for a while, preventing the chain from snapping and granting you a few previous seconds to get into position or out of a trap before the chain snaps and the blocks come crashing down.
Fruit and Money. The items are released from blocks as lines are completed, their sole purpose is to increase your score. Some objects are worth more than others. These scores are doubled or trebbled if they come from a bonus block.
Diamonds. ..are a girl's best friend. Complete 2 or more rows at once and you'll get a diamond. A regular diamond for 2 rows, an emerald for 3 and a saphire for 4. Collect these gems and you'll receive a serious boost to your score... which is important as extra lives and timeouts are linked to your score.