I have a blown speaker in the rear of my grand am. I was wondering if anyone had any suggestions on a good replacement speaker. Thanks.

Pretty sure your rears are 4x6's.

I'd try looking at www.crutchfield.com to see what fits you budget and taste of listening quality.
You can fit 6x9's in the rear too.
They need mounted from below the dash panel, instead of on top of like the factory one's.

A real pita to get them out.

I replaced my rear speakers, 6x9 by the way, with a set of Kickers. They sound nice and were relatively cheap online.

Everyone says to replace them from underneath but I removed the carpet piece from the rear deck and mine were held in by a trim ring with three clips. Very easy to replace once you get the carpet piece off of the rear deck.