usingle	One of my favourite: a basic singleton class from which one can inherit and create other singleton classes.
checkapi	API calls are checked vor valid results with this methods.
pdh	Simple interface to pdh.dll (not complete, but enough for monitoring CPU, no of threads, memory usage ... as you see it in Threads)
dict	Unlike TStringList, TDictionaryStrings takes advantage of the sorted property when using Values and Names.
singleinst	Full source code for a component which handles single instance requirement, and running in tray abilities