Floating Notificationsplay.google.com.floating.notifications
It can take a notification from any app and present it to you as a floating icon, similar to Facebook chat heads, but for any application. It even works in fullscreen mode (in Games, Youtube etc) and is fully customizable.

Themes:

• Any issues, requests or suggestions?
• Follow us on Twitter (@FNforAndroid)
• Like us on Facebook (http://www.facebook.com/floatingnotifications)
• Circle us on Google Plus (http://gplus.to/chatheads)
• Get beta access by joining the community (http://gplus.to/fnbeta)
• Or email us at support@iamrobj.com

Icon by FineTalent of XDA - http://forum.xda-developers.com/member.php?u=4841935

App integration:

• FN is not able to make notifications disappear from your status bar. An app cannot dismiss another apps notification.
• However, if you want any of your favourite apps to either make their status bar notification disappear when you dismiss the corresponding Floating Notification, or vica versa, you can point them to this page where they can add Floating Notifications integration:
• https://code.google.com/p/floating-notifications/wiki/API

Halo
This is NOT Halo. There are no popups of full apps and nor will there ever be. If that is what you are after unfortunately you will not find it here.

What's in this version: (Updated : Jul 29, 2013)

• 4.3 support - Uses the new notification listener service
• Card styled UI
• Enhanced theme engine
• Other apps now require a permission to remove FN's (apps such as NiLS)
• Minor bug fixes

Required Android O/S : 3.0+