I still use my N900 as a backup handset when my N9 is not available. It has one of the best media players - OpenMediaPlayer (OMP). I also like to use it as a serveilance camera with Watchdog app.

I'm pretty content with what's already available, but the ones available could sure use some updates or perhaps a new one that is up to date. For example, I use Twitter and Facebook frequently, as much as the web browser. While there are apps like Tweetian, and the port of Rocket, it would be nice to have one that has updated features like ability to tag (10) people in a photo. There's also video and GIF upload now. I also love the ability to copy a tweet URL and/or quoting, and viewing conversations. TwimGo and Tweed Suit were my favorites but no longer work for me.

The same with Facebook. Facebook has a lot of new features where the native app on Maemo is incapable. There are some other social networks I'm interested in such Instagram, Snapchat, Vine, Periscope, but there doesn't seem any way to access them besides through the web browser.

Although there's one I think would be really good, and that is an application that lets us broadcast live streams to popular services such as Twitch, YouTube, Ustream, WatchPeopleCode, etc.
Bambuser does this, and I like using that, but it's only for Bambuser site. It would really awesome if it supports custom RTMP server so we can direct it to certain IP addresses/any service we want. Something along lines of OBS, which is what I use on the PC to stream my desktop and video games I play. I plan on using my Nokia devices to live stream while on-the-go. I'd love to see a project like that exist. If you need someone to design icons and pieces of graphics, I'd be obliged to help build it.