I use quite a few, but one that works and works well is SampleE from aminet:
http://aminet.net/package/mus/edit/SampleEThis has the added advantage of being able to work with HUGE audio files (ie, larger files than your RAM capacity, without virtual memory)...hard disk size permitting of course. It's highly configurable too, you can save the position of each window. You can load/save .wav .aiff .iff or raw and all in 8bit/16bit and mono/stereo options. It will also upsample or downsample and you can also apply some effects and fade in/out etc.
There's also SampleZ which is exactly the same program, but a slightly updated version.
