Hi @allenyang! 
Below are some initial things that come to mind after working with a bunch of business-focused apps. I know there are some APIs, workarounds, and plugins already out there to help, but most of the time I just wish this stuff was built-in to keep things a little less Frankenstein.
Also, these items are less about a specific 3rd party platform and more about the fact that I often turn to 3rd parties to get these features.
Charts
The Bubble plugin only does one series and you can’t customize the colors. This is a super basic plugin that I see folks abandoning quickly the moment they want to customize any part of how it looks. A multi-series option with full control over axis labels, min/max, steps, etc. would go a really long way for apps with reporting dashboards.
Again, I know there are other plugins and if you’re sorta comfortable with HTML/CSS you can grab code from Google charts (or AMCharts, HighCharts, etc.) to keep moving forward, but really wish there was more baked in here.
Web Push Notifications
OneSignal seems to be the favorite, so it would be killer to have a more direct way to involve the API and do targeted notifications to users/devices.
Any app that wants to send an update to its users would benefit: marketplaces, apps with in-app messaging, social network type apps, etc.
HTML Emails
Many Bubblers are using Sendgrid templates for this, but it would be so nice to have a way to design emails out of the box so that dynamic data (text, images, etc.) is easier to manage.
With HTML Emails you’d be able to:
- Send more professional-looking branded emails
- Add tables to emails (e.g. questionnaire results)
- Clickable buttons (e.g. “Click here to confirm”)
That’s all I’ve got for now!