Maplestory Thief Edition Save Editor can be found at:
http://transport.to/maplethief/

I was messing around and saw that the saves for that game had no protection (checksums, etc.) so I reverse-engineered the file format and created a web-app for modifying the saves. This web-application and its source was programmed in the Adobe Flex framework and is released under the Creative Commons Attribution 3.0 Unported License so feel free to download/inspect/use the source in any way.

There is little bounds-checking in the program, so be reasonable when setting values as it may crash the game if its unable to load it.

Most inventory slots will show "no data" as the name for now because I haven't compiled a list of item ID to name mappings (yet).

Hacks Available (either directly or indirectly through modification of various properties):
- Level
- MP/HP
- Skill Points
- Instant Job Switcher
- Always Critical
- High Avoidability
- Full Inventory Customization (duplicate items; add/remove/replace items at will; ability to shift items up or down the list)
- equipment statistics (attack, defence, etc.) modification
- modifying equipment statistics allows for:
--- extreme damage
--- "always miss" effect (invulnerbility).
--- immense HP/MP
--- unlimited scrolling
- Bypass "master level" skill cap and get 99 pts for every skill (dark sight actually gives you mana instead of subtracting it)
- Unlimited equipment scrolling
- Mesos hack
- Skill Level direct editing

all of these properties are fully customizable unlike some other trainers which force a certain set of hacks upon patching of the file.

Screenshots (will stretch screen if directly embedded here):
http://img715.imageshack.us/img715/2521/capture3q.png
http://img202.imageshack.us/img202/4166/img0044f.png