Depends on your budget and what you want them to look like.
There's the skid row wine rack made from old wooden pallets.
A simple scalloped wine rack like these
can be built using an 8" (?) board and a 4" (?) hole saw. Space the holes in the board and then rip it down the middle, voila, front and back shelves. Repeat for every additional shelf and assemble.
I'm making (a project I've been slacking on) two custom 80 bottle racks similar to these
. I used 1x2s for the frame and shelves and then 3/4" x 3/4" molding for the 9" spacers. I'm assembling using pocket screws and wood glue.
There are these racks where the shelves are vertical
and the spacers support the wine bottle. I kind of wish I went in this direction because I think the staining and assembly would be easier. I think this rack is pretty similar
and has plans (but it's for 169 bottles). And I think you have to be a member to see the pics.
That Wine Racks America site has a lot of bottle measurements
handy for spacing.