I've seen a lot of people do nice work with Tru-oil. On OLF (luthier's forum) I read about a guy who was doing some tests. His results:
"I did just finish a month long experiment testing various finishes on maple fretboards. The best results occurred with wipe on finishes.....Tru-oil and Minwax gloss urethane both achieved a very nice, smooth sealed surface. Both are harder than shellac. The Minwax gloss is very easy to apply and can be flattened with 0000 steel wool or highly polished with compound.
Minwax wipe-on has my vote so far with maple. It's easy and durable. I haven't tried it on darker woods but this is my clear choice for lighter woods."