A few very random thoughts/ideas...
Just because free treats are the tradition doesn't mean you have to continue that tradition. Alternately a donation/tip jar set up where the treats are served might be of some use.
Perhaps an end of year letter to library patrons and local businesses soliciting donations. In the letter include a donation form that allows patrons to express the kinds of books or other media and genres they prefer to see their donations used for. Also perhaps a breakdown with the average costs of hardcovers, paperbacks etc. that the library buys.
There are various grants libraries can apply for...
http://librarygrants.blogspot.com/
Sell bricks with donor names on them to be included in some way to the library grounds
Setup something with some local businesses where you pay them X amount for coupons worth Y amount and sell coupon books. Kind of a very localized Groupon.
A wine, beer, chocolate, food tasting event. Where you organize and promote in conjunction with a local business and get a percentage of that nights take.
A Read-A-Thon
Silent Auction
Quilt Raffle
A community cookbook
Unfortunately I find most of the time the problem becomes that everyone thinks fundraising a great idea until there is a need for people to help with putting the event on or selling the raffle tickets/cookbooks/coupons etc.