The Dragon and I just got back from the library, and we were able to find old hard cover copies of The Mystery of the Stuttering Parrot and The Mystery of the Death Trap Mine. I didn’t realize that there are like 50 books in that series! (All by many different authors no less.) It took me a bit of time to come up with a search string that would ferret them out. (As well as going by an older book in the series that listed the titles of some of the others, but not the authors…) 
Another series I ran across that I haven’t seen mentioned is the Tom Swift series of sci-fi adventures! Set in the middle of a space race between two mythical super-powers, they have titles like Tom Swift and his Flying Lab and Tom Swift In the Race to the Moon..and about a dozen or so others. I always enjoyed those books because they had a jules Verne kinda feel to them. It’s amazing to note how many of the things that they have discussed have actually come to pass. (Deep see submersibles, high speed boats. space shuttles, satellites, etc…) Not bad considering they were written in the 50’s! 
Oh! The other series I have been looking for is the Sime/Gen series by Jean Lorrah. It describes a land where there has been selective mutation of human stock to produce two sub-species. Gen’s are pretty much normal, but simes are a sub-species that have tentacles that come out of their wrists at puberty which they use to feed off of the life energy of the gens. It’s really great. (In my opinion anyhow.)
I was always into anything interesting, be it history, philosophy, fantasy, sci-fi, or mystery. I too read the Encyclopedia Brown Series as well as Hardy Boys / Nancy Drew and such. (I was able to find a book of one minute mysteries by the author of the EB series this last winter. It brought back great memories of lying on my bed, reading the EB mysteries and trying to find the clue that I had missed in the story! ) 