File explorer - Solid Explorer, very good and reliable with lots of features
BBC - news and weather apps .
Pulse - Very good news type application, provides feeds in a easy smartphone format lots of content to setup, I use it as my main news reader and have things like Hexus news hooked up to it.
netflix (if you have it ).
Google hangout - this is being upgraded to have SMS functionality and stuff so its definitely worth using its brilliant as an IM.
Google Music, great player if you have your music on a play account (can upload 20k tracks to library for free or pay £9 or £10 per month for unlimited access)
tTorrent - Great if you have unlimited data and need to torrent, very quick and reliable (IME)
Viral - Like youtube but better, can have videos in "popups" so you can have a video overlay something and another major plus is the fact you can choose youtube video streaming settings i.e stream 720p or 1080p streams where as Googles youtube app seems a bit nasty for mobile connections and will just go "HQ or HD" which is really like 480p , worth a try if you watch youtube alot .
VLC - Good media player if you need it, cant fault it.
TV Guide - Got virgin media? use this to get a tv guide and set your tiVo to record remotely
Swiftkey - Very good keyboard if you dont get on with yours its certainly worth a try, takes a few days for it to start learning your typing but it gets good in the end.
Office Calculator - Like this calculator simply because you can do nice stuff with it and all the workings are saved so you can do many things at once, better than stock
Kingson office - Good free office application if you need it, Google drive covers alot of it now though
Only things that pop in mind at the moment, definitely recommend 99% of the Google Applications as they're generally solid .
Enjoy!