Update
Worked a bit on the assembler, I have a basic framework up and running for an assembler.

Update
It assembles most programs, and I started the real work on the GUI.

Update
I got source control set up, and moved the project onto Codeplex.  You can take a look here: tiDE.  If you are interested in joining the team, please send me a PM.  You should have experience with C# and run Windows, as well as have some sort of Visual Studio 2010 installed with TFS.  (If you are having issues setting up TFS, I can help.)

Update
Hello,
I've added full support for TI-Nspire projects, and at this point, you can use tiDE to compile TI-Nspire C programs.  I will add support for ncubate soon, as well as extend the current support for TI-Nspire projects.  I've also partially added file creation based on XML templates in a similar manner to project templates (see the last update).  The IDE portion is really fleshed out quite far.  As for the z80 assembler and z80 emulator, progress as usual.  We've also added projects for tokenizers (TI-Basic support).  A fully working sprite editor has also been added (with grayscale support), and will be made more and more functional over time.  It also accepts customized parameters from tiDE, so that a particular format can be accepted (TI-Basic has text sprites, assembly uses "db", C uses arrays, etc), which of course can tie into add-ins for more languages.  A DCS7 GUI editor has also been added, only partially in progress, to give an experience very similar to designing forms in Visual Studio.

As always, you can download the latest source code here.  Today marks the first day where you might actually want to get tiDE, for Nspire C programming (which is now fully supported).  Of course, it will be better in a few days, when integrated emulator support is added, as well as some more features to the suite as a whole.

Update
I just had tiDE assemble "ld (6 + 8 * 14h / %11011 - 'b'), a" correctly.  The math engine in tiDE is now working, folks, with a couple of easily fixed exceptions (for instance, the linker overwrites referenced values, when it should add to them instead, meaning things like "LabelNameHere + 2" end up as just "LabelNameHere").
Now, I pose to the community a question: when do you use parenthesis in your immediate values?  Do I have to add those?  I ask because it will be tricky with stuff like:
ld a, (2 + (5 - 2) * 3)

Update
This is a pretty major update, and quite a few things have been added since the last one.

Major Changes
*TI-Basic and Axe Support
   -This is pretty basic at the moment.  Only Tokenization is supported, and Axe doesn't compile, it just tokenizes into 8xp source.
*Code Completion
   -As you type, it will pull up a small window with all of the things you're probably about to type (type "Di" and the list includes "Disp"), and allows you to auto-complete it by pressing Enter.  This works for TI-Basic, Axe, and z80 Assembly
*Inline Documentation
   -This ties in with code completion.  For z80 assembly only (for now), hovering the mouse over text will give you information about it (opcodes give you size, clock speed, etc, and bcalls give you WikiTI documentation).  Also, code completion will give you documentation on z80 commands and bcalls as you type.
*Keyboard Customization
   -You can now customize keyboard shortcuts in tiDE however you like
*Latest News Feed
   -The Start Page (this shows up when you run tiDE) now shows a feed with recent posts from Omnimaga and Cemetech (either or both may be disabled) in addition to your recent projects.
*Global Settings Manager
   -I've added an extensible way for me to easily add user-controlled settings to tiDE, which automatically populate the Global Settings Dialog so you can edit them.
*Custom Tools
   -Parts of tiDE are still a bit buggy - you can use Custom Tools, however, to run external programs such as Spasm or WabbitEmu and still use the rest of tiDE's features
*Auto-Replacement
   -This is an optional feature for TI-Basic and Axe that allows you to automatically replace what you type, as you type it, with the appropriate symbols.  For instance, type "->" and it will automatically be converted to "→"
*Find and Replace
   -You can now use the Find and Replace dialog to search for and replace text.  This also has support for regular expressions.
*Source Insight
   -A system has been added to provide automatic insight into information about code.  This is most visible when expanding files in the solution explorer - you get a list of labels to jump directly to.
*Code Folding
   -You may now collapse items (in z80 assembly, these are labels, in TI-Basic, If-Then, While, Repeat, and For( loops) to their definitions, thus uncluttering your source code view.

Minor Changes
Fixed issue with $, fixed subversion, started converting assembler to run as standalone program, added context menu to code view, fixed signed literals, fixed bit instructions using IX/IY, added more comment syntaxes (// and /**/), added the ability for projects to have custom configuration by type (you can see this when creating a program - it prompts for a name)