Fallout 3 GOTY - chance to get it cheaper?

Most Likely Yes, probably 75% off

Pretty definitely.

As a daily, yes. I imagine the whole Fallout franchise will be a daily at some point

This is how you go about finding if a game goes on a better sale,

If the sale lasts the entire Summer Sale time then wait until the last day to see if it gets a Daily.

I was thinking about getting it, but my friend pointed out to me that it uses GFWL, and I was immediately turned off from making my purchase....

Perhaps it was cheaper, then I might go ahead and get it....

EDIT: I checked the store page and it doesn't even say anything about GFWL...maybe he was mistaken? Ugh, decisions, decisions....

I bought it a year ago when it was US$7.50, so pretty sure it'll get cheaper still.

edit: maybe not a year but still. :p

It should be -75% sometime (as should New Vegas.)