I've been making extensive use of the ABC(Plus) Music typesetting system. Rather than a single program, it is a collection of utilities by different authors. I've found need to augment or rewrite some of these utilities:

nwctxt2abc 0.3
This is an experimental NoteWorthy Composer 2 notation clip Text (NWCTXT) to ABC conversion utility.

Although my software can handle entire (and multiple) tunes in NWCTXT format, this utility page just accepts short NoteWorthyComposerClip text clips, converts them and passes the ABC result onto one of the online ABC viewer pages.

abcpp 1.4.4
This is a rewrite of Guido Gonzato's abcpp 1.3.2 from his ABC SourceForge page. He has this software and should eventually update his page. This program is a macro preprocessor for ABC, ala cpp for C, but also includes several other useful source transformations.

This revision fixes many bugs in the original (including Security Advisory SA13524), adds several new switches, folds in many of D. Glenn Arthur's ideas, increases MAX_MACROS per Hudon Lacerda's MICROABC, can handle recursion, no longer looks inside ABC constructs that it shouldn't, etc. For the details, see my changes log.

abc2prt 1.1.1
This is a rewrite of Guido Gonzato's abc2prt 1.0.2 from his ABC SourceForge page. He has this software and should eventually update his page. This program can be used to extract individual voices from a multiple voice ABC source.

This version ignores comments, removes %%staves commands before or after K:, allows both -vVOICE and -v VOICE style arguments to match Guido's Web documentation, plus fixes several bugs.

transpose_abc.pl version 2.2
This is my rework of Matthew J. Fisher's original script which fixes bugs, improves performance, adds support for inline key changes, ignores %%begin*/%%end* blocks, and changes argument order for use in Unix pipes. This software is also available from Jef Moine's ABC software page. As the name implies, this Perl script can be used to transpose ABC source files from one key to another.

Due to the original algorithm being preserved, some of the transpositions produced are audibly correct but can be enharmonically incorrect as printed which I hope to address in a future update.

!caesura! decoration
A tiny *.fmt file you can include via -F, when compiling your source with abcm2ps, that adds caesura (railroad tracks) decorations:

| z E2 | z F2 !caesura! | z D2 |

Reminder accidentals
If you use my current abcpp above, then you can define crude reminder accidentals in ABCPlus via:

#define (_) y10"@-20,-4(\\b)"
#define (=) y10"@-20,-5.5(\\=)"
#define (^) y10"@-20,-5(\\#)"

and use them in your ABC music notation via:

C (=)D (_)E | ^F (_)E (^)F |

At least until we get the real thing...