PPM is yet another Game Boy (Color) tile and map editor that uses GTK. It supports many export formats (raw binary, GBDK .c, ISAS .asm, TASM .asm, WLA .asm, and RGBDS .asm), and has different Game Boy Color color emulation modes. It can also import GBTD and GBMB (popular tile and map editors for Windows) files. All mouse buttons draw, and there are loads of keyboard shortcuts. It can also optionally emulate the Game Boy's display.
WLA DX is yet another macro assembler that can program the GB-Z80, Z80, 6502, 65c02, 6510, 65816, HuC6280, and SPC-700 CPUs. Included in the package there is a GB-Z80 disassembler and few converters. WLA DX was initially programmed to compile ROM images for Gameboy, but nowadays it can also patch existing ROM images with code, and even compile program files and ROM files for other CPUs like the NES-6502, C64-6510, and SNES's SPC-700.