There are many Useful applications available But all depends on wat u want.  Visit OVI Store to download such apps.

For example Try "SWYPE".

*Spark Beta is the Ultimate Active Home Screen with Live Twitter & Facebook Social Streams, Live Breaking News, Entertainment, Sports and Top News categories all live on your Phonetop. Update Twitter & Facebook at Once! Blog or Share News To Facebook, Twitter or SMS. View the Weather Forecast Wherever You Are With *Spark ’s Location-aware Weather Module. *Spark will turn your phone into a Home-Sweet Phone.



Beta available at Ovi Store: http://store.ovi.com/content/56538

Developer's site: http://www.sparkmyphone.com/getit.php
P.S. Another nice app (i suppose) which is still in beta stage, haven't tried yet, if u hav itchy hands, can go ahead and tell us about it 

immediately after startup, 53MB. After using it as normal, ±45MB

Hey, I just found a new trick to play with. You guys with slideunlock, put 1 finger at the button, then 1 more finger at the target location. Quick slideunlock

The return of Jason!! Long time no see you already...see my stars

When I saw .005 I wanted to yell, HOW...luckily saw the V20 in front

Everything under the removable tab 

Immediate RAM payroll time! 

Touch Vista FTW! Basic themes hurt my eyes 

For sure. You want a link? It is quite large too...5MB... but really it looks good...the icons are good...the skin is plain black... and with just with little splashes of neon green to brighten it up.  I have been using it exactly like a default theme. Never changed since I got it
My mom's 5700 also using it. Her's is 3rd, mine is 5th 
It goes down well with the old folks and the young who think old like me 

http://www.tehkseven.net/nokia-themes-tehk...pecial-edition/
only for you my dear sifu 
Install the 5th to your X6 ya

Just go to update it 

Not at all man! I'm very very bad. that's why
argh, I need to study now. Bye.