What other doughs/breads can I raise with my liquid levain?

I'll make some guesses, although that is all they are.

1. Baker's preference.  A particular levain, or group of levains, may provide the leavening and flavor characteristics that the baker desires for the finished bread.

2. Like levains and breads (rye/rye, white/baguette, etc.) mean that the microflora already inhabiting the levain are accustomed to the flours that are predominant in the formula.  Thus, no adjustment period for the bacteria and yeasts in the levain when they are mixed with the rest of the flour in the dough.

You can use virtually any levain for any formula calling for levain.  Using a rye levain for your baguettes will leave traces of rye in the finished baguette, which is not tres chic (but will taste very good).  It's your bread, you can build it as you please.  It will not be precisely what the formula developer envisioned but there's no way you can exactly duplicate the ingredients and conditions that s/he used, anyway.  

Paul

I guess I'm not a purist and actually I didn't realize until recently that a lot of people match their levain flour to the bread they make with it (rye levain for rye bread,etc).I use AP flour simply because of the cost and availability. It works great for my whole wheat breads,french breads,and sweet breads. For rye I have used my AP starter some of the time and some of the time made a rye poolish with the Ap starter and rye flour for a rye loaf.

Do what works for you!

There are some bakers who maintain several starters meant for specific types of bread. Many - and I'd venture the vast majority of - home bakers keep to just one and build it out to suit an upcoming bread. It's just a heck of a lot simpler to keep things simple. And then some bakers have starters from different sources & places which gives different flavours and result.

It's entirely up to each one which works best for their situation. There is no "wrong" way.

I asked Jeffrey Hamelman about keeping various starters recently. He told me that he  keeps just two: a liquid white at 125% that's about 12 years old and a stiff rye that's a tad over 30 years. These are all he uses to pump out all his bakery's products; the rye for rye breads, the white for everything else. They convert the liquid to stiff or whole wheat as needed.

Jeffery says that for the home baker, there's little point of keeping more than one:

Small adjustments in flour or water will compensate at the time of the build so that levain consistency is correct. And if one maintains just a liquid or a firm white culture, he or she can easily give a couple of meals of rye flour in advance of making rye bread--that will suffice; there's no need for occasional rye bakers to perpetuate a rye culture. 

You can read the more detailed email exchange here. 

And to your first question, there are TONS of different breads that can be made with sourdough culture, some of them not in the least bit sour. Most any commercial yeast recipe can be converted to sourdough. You primarily need to adjust your times (it's a fair bit slower than the fast commercial yeast) and of course compensate for the flour and water from the starter. There's info on these boards on how to convert dried yeast recipes to sourdough.

Happy baking,

Paul 

Yumarama & MellowBakers