All platforms (except the still useless Windows Phone 7 and the ridiculously closed iOS): Opera Mobile 11! The best computer web browser now on your tablets and smartphones, doing a really great and amazing job, amazingly fast! (Posting this message from Opera Mobile 11 on Nokia N8)
Opera Mini also for all platforms (including iOS, except for WP7).
Best Symbian Games:
NFS Shift, Hero of Sparta (Gears Of War-lookalike), GT Racing Motor Academy, Avatar, Wooden Labirynth 3D, SpeedX, BOOM BLOX, Tetris, The Sims 3, Asphalt 5, Raging Thunder 2 (internet crossplatform racing multiplayer!
watch my sister playing it HERE), Tom Clancy's HAWX, Pro Evolution Soccer 2011, Monopoly, Fruit Ninja, Assassin's Creed, The Settlers, Spiderman, UNO, BOOM BEATS (PSP game), Real Football 2010, Real Golf 2010, UNO, I Must Run, WarChess, Worms HD, Fuzzies, etc
Great apps:
Gravity (Twitter and FB app)
Opera Mobile 11 and Opera Mini 6 (simply awesome)
Soundhound and Shazam
Skype
Qik (video calling and live broadcast online)
Slick (fully featured messenger for AIM, FB, MSN, ICQ, Google talk and others), Layar (augmented reality)
Compass
Youtube
Sports Tracker
SymTorrent (fully featured torrent client with support for resuming downloads, multiple connections, checking hash of files already downloaded both oncthe phone and on pc that have been transported to continue download on the phone, managing torrent files, + choose which files to download, etc)
Nokia BigScreen (just like Windows Media Center in HD, but on the phone at 1280x720p @60fps via HDMI to your full HD TV!. Features: karaoke, HD movies with subtitles, music/photos/etc
watch it in action (NB: not beta anymore!))
And many more, I just don't have time to type them here