Reddit has a good community too, it mostly has people posting their finished results with varying degrees of implementation detail.
I've only recently finished working my way through the official starter-kit project-list - so I'm only a beginner myself - right now I'm just waiting for a bunch of new sensors/hardware to ship from AliExpress. Hopefully once it does I'll be able to build an MP3-player, NTP-based clock, etc. Nothing too novel, but fun regardless I hope!
Finally https://www.hackster.io/arduino has a few nice projects, as does instructables. As with any of those kind of sites the projects/clarity vary.