Yesterday I played Mondi Confinanti’s “Little Falls”, a Glulx horror/thriller game. It’s short (less than an hour to play once), with few puzzles, largely relying on atmosphere; it provides full illustration and sound effects. I had mixed feelings — fuller review to follow — but I was impressed by the polish and effort, and probably would have found it more effective if I hadn’t gotten stuck on something stupid for quite a long time. If you enjoy horror or are interested in multimedia IF, it’s worth a look. There’s a page on the game and a download page.
A few weeks back, I played and enjoyed Jon Ingold’s “Dead Cities” from the Lovecraft Commonplace Book Project. I’ve yet to try anything else from that set, partly because “Dead Cities” was so cool I wanted to just let it stand on its own for a while. Wonderfully atmospheric, with some creepy, visionary elements.
Also worth a look: Eric Eve’s “Blighted Isle” (Zip file here). I beta-tested, so will not be reviewing it, and a few things may have changed since I tried it. But it is a sizable historical piece with multiple endings, a large host of characters, and the care and polish you would expect from Eve.
Emily Short's Interactive Storytelling 
How did they get graphics AND sounds into inform?
I thought you guys only released the graphics plug-in.
Inform 6 can do graphics and sounds; it’s just that Inform 7 hasn’t (yet) picked up the sound features.
Must…have…patience… :)
…and, in fact, the new build just up introduces rudimentary sound support to I7 for the first time.
But doesn’t I7 just use I6 under the hood? Theoretically (unless I’m misinterpreting here…) you could use the I6 programming language for the sound needs and then use I7 natural language for everything else. Or is there a fundamentally different interpreter along with I7?
You can use the I6 language for advanced Glulx work, yes — but the built-in interpreters in the Inform application do not all yet honor all of these features. So you might find yourself in the odd situation of having created a game that could be released and tested on another interpreter, but which not play properly on the internal interpreter.
All that is obviously not ideal, and is being worked on for future releases. (As, indeed, the latest Windows version does away with many restrictions on what the built-in interpreter can do graphically, bringing it in line with the Macintosh application in that regard.)