I've participated in many bake sales (aka "cake sales" or even "cake mornings" here) and brownies have been very popular. Chocolate cakes, especially with chocolate frosting, are big hits. Coffee cakes (which in the UK means a cake with coffee in the batter, not the Sara Lee style US coffee cake!) are popular too. Trays/bags of small items like single cupcakes or 3-4 cookies/biscuits or 1-2 brownies are popular with families, and especially with children who may want to spend their pocket change. Anything which you make clear "Can be frozen up to 3 months" will sell at this time of year as people are starting to think ahead to the upcoming holidays and stocking their freezers.
We've had home baked bread loaves at our bake sales but they have never been popular and have sold poorly - if they sold at all! I would not recommend asking for bread loaves (or rolls, or baps, or anything along those lines).
Something I do is mix up my pound cake batter, which makes a really big pound cake, and bake it in 2-3 loaf tins, wrap it up well and label it "Madeira cake - can be frozen" and it always sells quickly. Another thing I did was make a big batch of peanut brittle. I broke down the pieces and divided it up into small bags. It didn't sell until I started handing out free samples. Then I sold out completely in 30 minutes!

I also have a good supply of those colored Reynolds Wrap plastic wraps and I do "rainbow wrapping" of cupcakes etc. Makes a very colorful display and grabs people's attention - especially since the colored "cling film" is a real novelty here.
I also recommend asking contributors to list their ingredients, especially if the cakes contain NUTS. This is because of people with food allergies.
Our last fundraising cake sale raised over £600 for charity, so be prepared for some hard work and a whole lot of dishwashing, but a great and really fun day!