Yesterday I started to fiddle around with Nucleus OS (the underlying Operating System of the Nspire) and here is the first tool I wrote for it: A Task Manager
It shows the currently running tasks, infos about them and it can kill tasks

Currently it only works on classic non-CAS Nspires (it shouldn't be hard to add support for other models, but I am lazy...)
More features will come.

Known tasks:
gui - User Interface. Killing it crashes calc
KPD_TASK, KPT_TASK - Handle keypad input. Killing them makes the keypad unusable
wcm_* - probably related to the wireless cradle?
OffMon - When killed you can't turn the calc off

Well, I haven't tried it too much, but you shouldn't kill gui because it'll crash your calc
And for some tasks it is hard to find out what they do, either because they have no names, or a name that doesn't say anything about their purpose...

I haven't tested it on real hardware yet (because CAS is running on my calc and that's not supported atm) so thanks for doing that
I don't think killing a task will corrupt or damage anything, but I can't guarantee it (but even if it does, which is unlikely, you can still reflash the OS )

Maybe wirte a feature that allows you to explore, to a greater extent, the purpose of a task and/or what and/or how it does what it is doing? Monitor the CPU for different things like I/O and the memory section with a viewer for the selected task? A scheduler and a performance monitor, as well as a memory viewer, is always a nice feature I give ideas! I don't know how to implement them yet

Interesting
I've spread out the word to TI-Planet: https://tiplanet.org/forum/viewtopic.php?f=17&t=11414

Added support for CAS as I wanted to test it...
#ifndef SYSCALLS_H
#define SYSCALLS_H

/* Task */

static const unsigned int tcf_established_tasks_addrs[] = { 0x102F0C1C, 0x102F1348, 0x0, 0x10 };
#define TCF_Established_Tasks SYSCALL_CUSTOM(tcf_established_tasks_addrs, unsigned, void)

static const unsigned int tcc_current_task_pointer_addrs[] = { 0x102EFBF4, 0x102F0320, 0x0, 0x0 };
#define TCC_Current_Task_Pointer SYSCALL_CUSTOM(tcc_current_task_pointer_addrs, void*, void)

static const unsigned int tcf_task_information_addrs[] = { 0x102F0D10, 0x102F143C, 0x0, 0x0 };
#define TCF_Task_Information SYSCALL_CUSTOM(tcf_task_information_addrs, int, void*, char*, unsigned char*, unsigned*, unsigned char*, unsigned char*, unsigned*, void**, unsigned*, unsigned*)

static const unsigned int tcf_task_pointers_addrs[] = { 0x102F0E80, 0x102F15AC, 0x0, 0x0 };
#define TCF_Task_Pointers SYSCALL_CUSTOM(tcf_task_pointers_addrs, unsigned, void**, unsigned)

static const unsigned int tcc_terminate_task_addrs[] = { 0x102F06C0, 0x102F0DEC, 0x0, 0x0 };
#define TCC_Terminate_Task SYSCALL_CUSTOM(tcc_terminate_task_addrs, unsigned, void*)

/* Dynamic memory */

static const unsigned int dmf_established_memory_pools_addrs[] = { 0x10273948, 0x10274074, 0x0, 0x0 };
#define DMF_Established_Memory_Pools SYSCALL_CUSTOM(dmf_established_memory_pools_addrs, unsigned, void)

static const unsigned int dmf_memory_pool_information_addrs[] = { 0x10273960, 0x1027408C, 0x0, 0x0 };
#define DMF_Memory_Pool_Information SYSCALL_CUSTOM(dmf_memory_pool_information_addrs, unsigned, void*, char*, void**, unsigned*, unsigned*, unsigned*, unsigned char*, unsigned*, void*)

static const unsigned int dmf_memory_pool_pointers_addrs[] = { 0x10273A6C, 0x10274198, 0x0, 0x0 };
#define DMF_Memory_Pool_Pointers SYSCALL_CUSTOM(dmf_memory_pool_pointers_addrs, unsigned, void**, unsigned)

static const unsigned int dmc_delete_memory_pool_addrs[] = { 0x10277C28, 0x10278354, 0x0, 0x0 };
#define DMC_Delete_Memory_Pool SYSCALL_CUSTOM(dmc_delete_memory_pool_addrs, unsigned, void*)

#endif

Idcmigrate is quite buggy, so I did it by hand (it was really easy since all I had to do was to match the lines in the xrefs of TCT_Check_Stack).

Also: File->Produce File->Dump database into IDC file . (Warning: some personal informations are dumped in this file, like licence information, paths (if you have your real name as username)... )

And another update that allows you to view event groups and queues (non-CAS only, tasks and memory pools work on CAS/non-CAS, thanks excale)
I have fixed the grayscale bug (the background is white now as it should be) and added double buffering to Nspire I/O (no flickering anymore).
In the new settings menu you can enable interrupts. When interrupts are on, you can see the event queue filling up when pressing refresh