Developing JNI routines for Windows - want your suggestions

Question

Everyone:
After seeing several questions over and over again about how to do certain things that can only be done (or at least best be done using JNI), I am taking the time to develop some java/c code to access native Windows functions from Java.
Please make suggestions as to functions you wish you had through java but do not. Common requests are: reading environment variables, setting system time, date, getting mac address, etc. The more you ask for, the more the library will be able to do. Once it's working, I'll post the code here for anyone who wants it.
Thanks.

Answer 1

Updated list of jni functions now supported (descriptions are self explanatory):
JNIEXPORT jstring JNICALL Java_Win32Native_sayHello (JNIEnv *env, jobject);
JNIEXPORT void JNICALL Java_Win32Native_setSystemTime (JNIEnv *env, jobject obj, jshort hour, jshort minutes);
JNIEXPORT jstring JNICALL Java_Win32Native_getMACAddress (JNIEnv *env, jobject obj);
JNIEXPORT jlong JNICALL Java_Win32Native_createMutex (JNIEnv *env, jobject obj, jstring strMutexName);
JNIEXPORT jlong JNICALL Java_Win32Native_getLastError (JNIEnv *env, jobject obj);
JNIEXPORT jlong JNICALL Java_Win32Native_getErrorCode (JNIEnv *env, jobject obj);
JNIEXPORT jboolean JNICALL Java_Win32Native_isRunning (JNIEnv *env, jobject obj, jstring strMutexName);
JNIEXPORT jstring JNICALL Java_Win32Native_getWindowsDirectory (JNIEnv *env, jobject obj);
JNIEXPORT jstring JNICALL Java_Win32Native_getSystemDirectory (JNIEnv *env, jobject obj);
JNIEXPORT jstring JNICALL Java_Win32Native_expandEnvironmentStrings (JNIEnv *env, jobject obj,jstring strSource);
JNIEXPORT void JNICALL Java_Win32Native_lockWorkstation (JNIEnv *env, jobject obj);
JNIEXPORT jstring JNICALL Java_Win32Native_getFileTime (JNIEnv *env, jobject obj, jstring strFileName);
JNIEXPORT jlong JNICALL Java_Win32Native_getTickCount (JNIEnv *env, jobject obj);
JNIEXPORT jdouble JNICALL Java_Win32Native_queryPerformanceFrequency (JNIEnv *env, jobject obj);
JNIEXPORT jdouble JNICALL Java_Win32Native_queryPerformanceCounter (JNIEnv *env, jobject obj);
JNIEXPORT jint JNICALL Java_Win32Native_getHwnd(JNIEnv *env, jobject obj, jstring title);
JNIEXPORT void JNICALL Java_Win32Native_setWindowAlwaysOnTop(JNIEnv *env, jclass obj, jint hwnd, jboolean flag);
JNIEXPORT jstring JNICALL Java_Win32Native_getDriveType(JNIEnv *env, jclass obj, jstring strPath);
JNIEXPORT jlong JNICALL Java_Win32Native_getDiskFreeSpace(JNIEnv *env, jclass obj, jstring strPath);
JNIEXPORT jstring JNICALL Java_Win32Native_getEnvironmentVariable(JNIEnv *env, jclass obj, jstring strVariable);
JNIEXPORT jboolean JNICALL Java_Win32Native_setEnvironmentVariable(JNIEnv *env, jclass obj, jstring strVariable, jstring strValue);
JNIEXPORT void JNICALL Java_Win32Native_rebootPC (JNIEnv *env, jobject obj);
JNIEXPORT jboolean JNICALL Java_Win32Native_moveFile(JNIEnv *env, jclass obj, jstring strSource, jstring strDestination);
JNIEXPORT jboolean JNICALL Java_Win32Native_installFilters(JNIEnv *env, jclass obj, jint hInstance, jstring strTitle, jlong tmNow);
JNIEXPORT jboolean JNICALL Java_Win32Native_killFilters(JNIEnv *env, jclass obj);
JNIEXPORT jlong JNICALL Java_Win32Native_getCurrentTime(JNIEnv *env, jobject obj);
JNIEXPORT jlong JNICALL Java_Win32Native_getHinstance(JNIEnv *env, jobject obj, jstring title);
JNIEXPORT jint JNICALL Java_Win32Native_createProcess(JNIEnv *env, jobject obj, jint nMode, jstring cmdproc, jstring buff );
JNIEXPORT jint JNICALL Java_Win32Native_createLink(JNIEnv *env, jobject obj, jstring strPathObj, jstring strPathLink, jstring strDesc );
JNIEXPORT void JNICALL Java_Win32Native_launchDefaultBrowser(JNIEnv *env, jobject obj, jstring strURL );
JNIEXPORT jboolean JNICALL Java_Win32Native_emptyBrowserCache(JNIEnv *env, jobject obj );
JNIEXPORT jboolean JNICALL Java_Win32Native_sendFileToRecycleBin(JNIEnv *env, jobject obj, jstring strFilePath);
Thanks to those who made suggestions. Certainly open to more ideas.