Newbie can't get plugin to show up in Effects menu

Where do you have your solution / source code? For my case, I use the BuildAll example (the one you get after installing the sdk). Before building the example, on Windows, change the value of the AE_PLUGIN_BUILD_DIR environment variable to where you install After Effects CS3. After build, all the *.aex files will be under plug-ins/sdk folder. When you run After Effects, the plug-ins shd be loaded properly and you can also debug it from Visual Studio.

Turns out, I was full of...misinformation. Or rather, outdated information.

AE CS3 Trial loads AEGPs just fine. There must be something else going on.

Confirm that the .aex files have valid PiPLs, and set breakpoints in your entry point function to see whether we're calling you at all.

I put the plugin into C:\Program Files\Adobe\Adobe After Effects CS3\Support Files\Plug-ins\Effects. It's the ProjDumper plugin that comes with the SDK. The guy I spoke to is Bruce Bullis. He said that AEGPs won't work in the trial version, or at least that's how I interpret what he did say: "Yes, if you're making an AEGP...The AEGP API exposes lots of functionality that's disabled in trial."--Rob

As Shachar mentioned, the plug-ins need to be in the plug-ins folder, not just in the application folder.

Also, did you restart After Effects? Plug-ins are loaded when the application starts.

See the "About plug-ins" section of After Effects CS3 Help on the Web for more information.

Regarding the trial version: Yes, it should load externally built plug-ins. There are some licensed third-party plug-ins that come with the full version of After Effects that are not included with the trial. Perhaps that what you're remembering being told. (Having said this, I'm going to go and double-check. If you can tell me which "guy at Adobe" you talked with, it will make my double-checking easier.)

--Todd, another guy at Adobe

I used a trial version of AE for a time while building plug-ins; worked fine for me.

I have it from a guy at Adobe that the trial version of After Effects won't load an externally built plugin. I guess I'll have to get my boss to spring for a real version.

given the code compiled correctly, all you need is the .aex file.
the .r and .rc are only used by the compiler.
the .aex belongs in the following path:

C:\Program Files\Adobe\Adobe After Effects CS3\Support Files\Plug-ins

or where ever you installed after effects at.
just make sure they're in the ...Support Files\Plug-ins

in the plug-ins directory you may create another folder to keep the plug-ins you create organized in one place.
AE will look in any folder in the plug-ins directory as long as it's name doesn't start with a tilda sign (~).

now where will they be found inside AE?
if they are effects (plug-ins that are to be applied to layers), then they'll be found in the effects menu.
unless you changed the category in the .r file they should appear in the "Sample Plug-ins" category in the effects menu.

if they are AEGPs (plug-ins that do operations as opposed to image processing) then they'll be in the category set in their .cpp file using the AEGP_InsertMenuCommand function.

if you put the files in the right place and they still woun't load, then they're probably invalid. (either built wrong, or not at all built)

b.t.w
if you start a debug session using visual studio, it prompts you for the afterFX.exe file.
once selected, visual studio should put the compiled plug-ins in the correct place.
at least it did for me.