Riffstation is still out there, you just have to hunt it down and its now free (it went up to around $25 I recall when I bought it years back, then support was pulled). 
I find it useful if I want to change the key of something and export the audio. Very quick way of transposing backing tracks, when experimenting on vox. Slow down works well also.
In addition to that I’ll use Transcribe! and Reaper if I am actually in a project but its also handy for dropping YouTube tracks in. YouTube is ok but not flexible enough in my opinion, with its fixed percentile speed changes. 