These are the apps which I have used for hours and they worked perfectly fine till now. App names contains links to marketplace and you can directly download these to your device.
This is a good app for engineering students and general knowledge research. It helps to draw graphs, find series for a group of numbers, finding facts. I've used this to enquire domain names and also english grammar definition. A must have app for every student and scholar.
This is a google reader app and i use it to read updates from rss subscriptions. It has a decent offline functionality and if you have enough memory on memory card, it can pre download full articles.
TuneIn Radio pro(premium)
I bought this app from google play(formally android market). It has access to all shoutcast streaming media. The pro version has recording options which means you can download streaming music. It has pretty decent playback and buffering experience. I certainly recommend this app.
This is a free anonymous proxy client on tor server network. This is useful for seaurely visiting any website without leaving any footprint. It slows down internet speed considerably. This is only needed for privacy connscious people and not for everyone.
YES!! Pdf files open seamlessly on galaxy 5 handset and i read quite heavyweight pdf files using this app. Works fine on text and images. But it takes lot of time in zooming on images. So use this if you have lots of text and little images to read.
This app shows a graph of upload and download speed in realtime. Although it uses significant amount of RAM yet i find it of utmost importance
Opera mini next(my favorite mobile browser)
I use this to view streaming videos and also audio and video files. Quite stable, clean interface, it is my favorite since i knocked out winamp and rockplayer. It is one of the best media players on android.
My Data Manager
I always ran out of data balance and ended up paying my balance for every megabyte of internet overage. But thanks to this app i can now limit monthly mobile internet usage to any value like 500 MB or 3 GB as i like. As soon as limit expires, this app turns red and notifies you for excess usage.
Air control lite(game)
Yes this is a nice game where you play the role of air traffic controller and land aircrafts, jets and helicopters on a landing strip. My personal best score is 200 after lots of hardwork.