The official Beepola site was actually offline for quite a while, but fortunately it's up and running again.
In case it goes offline again, I'm maintaining a mirror of the download here.

Also, if you want to dig into 1-bit music, be sure to check out the 1-bit forum.

I didn't see a post mentioning this at all so here you go. Here's a bit from the changelog.
Lazy I know....
v1.08.01 - 19/Dec/2013
----------------------
1. Fixed Edit->Pattern->Copy not copying all detune/skew values over.
2. Fix note entry when clicking on piano keyboard for Tritone and QChan.
3. Note indicators for channels 3&4 no longer erroneously show when editing
    songs using a 1 or 2 channel engine.
4. Now correctly sounds tritone note skew values when entering notes into a
    pattern.
5. Edit->Pattern->Expand->x2 and x3 now correctly expand skew values for
    tritone patterns.
6. Added new Edit->Pattern->Expand->x1.5
7. Edit->Pattern->Append... now correctly appends skew values for tritone.
8. Tools->Options->Emulation tab now contains an option for switching I/O
    port contention in Beepola's Spectrum emulation ON (original 48K/128K
    Spectrums) or OFF (+3, Timex, Pentagon and most other clones). Default
    is off.

v1.08.00 - 16/Dec/2013
----------------------
1. Huby engine now supports detuning.
2. Added QChan engine.
3. Added Tritone engine.
4. Added Tritone and QChan to song ripper.
5. VT-II import now creates tritone formatted, 3 channel songs.
6. Added manual import option to song ripper.

http://freestuff.grok.co.uk/beepola/