I would strongly recommend you get some lm328 chips if you are interested in speaker and audio projects, it a low cost amplifier on a chip. If you search around youtube you will find, ipod amplifiers, guitar amplifier etc etc all built using this great little chip.
I have one on an Audino Arduino based synthesisor, I simply copied the minimal circuit from the lm328 datasheet and use it to drive a pc speaker from the Arduino, its a great chip so but three or four.
You could also get some lm3916 chips and add a vu meter to your projects. they are both incredibly simple chips to use.
Duane B