[boldpanda]

I'm assuming Bitcoins can be bought in fractional denominations?

[ashray]

Most exchanges will ask you to buy at least $1 worth of bitcoins so that pushes your figure to about 0.001 BTC as a minimum purchase. However, you can certainly use them with up to 8 decimal places.

[studio816]

Yes. You can buy as little as 0.00000001 BTC aka "satoshi"

[archQuestions]

They can be divided down to 8 decimal places currently, yes.

[mattgibson]

Yes, divisible down to .00000001 (a Satoshi).