The classic jewellers saw is a highly versatile tool that can get into places and saw at angles that would otherwise be impossible. Most woodworkers buy one for releasing the waste between the tails and pins of through dovetails, but soon come to realise how useful they are for other jobs too.
I particularly like these adjustable frame jewellers saws; tensioning the blade is easier and if the blade breaks you can put the longest bit back in and carry on. The saws also have a blade tensioning screw at the front so you can install the blade in a civilised manner and then adjust the tension accurately. Lastly these jewellers saws take straightforward blades without any loops or pins at the end, so if you need to insert one through a very small hole to start in the middle of a piece, you can do so.
Superb quality, round backed, Swiss made 5" plain unpinned blades to fit sold separately.