Ok, so any device that gets release these days is more or less useless without the apps that can help in various daily tasks, and Glass is no different. The reason why platforms do this is because they simply don't want to develop apps as it would be too difficult and too expensive to cover such a broad range of applications.
Leave that to the experts. Google are calling the Glass apps as Glassware. Get it?... it's a combination of the words glass and software……… yeah! Ok, silliness aside, there are currently exactly 73 apps at the time of this writing, and I've probably tested only a small handful of them.
There's a reason for this, it's because there is only a limited amount of storage on the Glass so it's hard to install too many apps, and in fact most of the apps only work in the US with US services. For example, Opentable the restaurant bookings platform created and app for Glass but I can't reserve a table in the UK on it yet.
The problem that all the apps will face is that the Glass screen is just so small and limited in how it can display things. On searching for an article via Google, I can get brief summary results show up but they only read about 30 words and then I need to click again to read more. Cue the clunky interface to read. Why anyone would want to read anything more than a sentence on Glass I really don't know. Of course Google themselves have added apps to integrate into their ecosystem. You can get Gmail, Google Calendar and Google Now as well as others. In fact the platform is so restrictive that to read your email on Glass, you must have it on your Gmail account.
Duolingo created an app, why I have no clue, but their legendary language learning courses app on mobile phones really doesn't translate to Glassware easily. For a start it relies on the user to self certify that they got the answer correctly instead of voice detection and then word matching. In all likelihood this is because of potential battery drain and data intensive transactions probably are going to kill the Glass.
Twitter is good, it's easy to post updates and see updates on your stream. You can configure which notifications you get via the Twitter preferences on their website. I was also trying out ShopX, a shopping list app designed to help you with your shopping out in supermarkets. It sucked, big time, and something as simple as a shopping list should be hard to make sucky, but they achieved it.
There are several news apps which merely flash up some latest news periodically. Pretty useless because if there is something I wanted to read immediately I'd still have to get out my phone to read in depth. There are also a variety of fitness or health related apps from ones which can help analyse a golf swing, to Zombie Run which adds an element of augmented reality to your daily runs.
Overall I haven't really found an app which I think totally rocks the Glass platform, and I think that isn't because they are bad app developers, I think it's because the Glass platform sucks in the first place. It's like people are trying to build Angry Birds for a Palm Pilot.