You can write lots of BASIC programs
Look the EDIT and CHAIN commands in the manual.
IS-FORTH also can use many memory.
HEASS assembler and HWP word processor can use all the available memory for the source/document. (For example my Zozotools source is 124K in .HEA, 247K in .TXT format. Before HEASS needed to use lots of include files, hard to overview the whole program. EXDOS disassembled source currently 181K in .HEA, 312K in .TXT)
Video and soundplayer from IstvanV also can use all the memory.
Some demos with large digital sound data also use more than 128K.