If you like Marble Hornets Might I suggest you look up TribeTwelve and MLAnderson0 as they both do excellent Slender Vlogs. TribeTwelve has very good Spec.FX relative to other series' and MLAnderson0 is of a superbly high quality, probably the best acted slender vlog.
If you are interested in something closer to an ARG, and don't mind doing a lot of additional research, then EveryManHYBRID is also great. But I do mean a
lot of additional research, only about 50% of the story takes place through their youtube channel, the rest is found in BlogTV sessions, regular written blogs, the twitter account and even direct audience participation. Don't let that put you off too much though, the amount of work the EMH guys have put in is truly staggering, making Marble Hornets look shallow; But you get out what you put in.
If you'd like to see a meticulously investigative hive mind pick apart each video, picture and tweet minutes after they're posted then I strongly suggest checking out the unfiction forums which have both a dedicated marble hornets section and a dedicated Slender Man section.
These people will, seriously, blow your mind; I've seen them find messages hidden in the Audio spectrum of videos. If there is a hidden frame, or an important symbol, or the slightest hint of a riddle these guys will have it sussed in no time whatsoever. They also help to illustrate just how much you miss just by watching the video
On the subject of slenderman, Its sort of the internet generations Bogey man. The Vlog series' are very much like Paranormal Activity, except, you know, scary.
