Has anybody found a hack for the Cricut?

My niece got one for Xmas. It's a bit of a ripoff in that they expect you to buy expensive new cartridges for different fonts and patterns. I found that you can cut vinyl with it and etch soft materials which is of interest to me.

I found a second party software program called “Sure Cuts A Lot” which eliminates the need for these cartridges and makes user created items possible still even that is not cheap.

Is there other perhaps an open source program which would work with this machine or a way to hack it to use it without restrictions?