cCalc offers the following features :

Number Keys and Basic Math Functions : Addition, Subtraction, Multiplication, Division.
Programmable Formula : User-Defined Functions i.e Tax and Currency Conversion Functions
Trigonometric Functions : Trigonometric/Inverse Trigonometric Functions (Sine, Cosine, Tangent/Arc Sine, Arc Cosine, Arc Tangent), Hyperbolic/Inverse Hyperbolic Functions. Degree/Radian/Grad mode for angle unit
Common Mathematical Functions : Logarithm, Power, Exponential, Reciprocal, Square Root
Pi Constant, Factorial Function
Base-N mode and Logical Operations : Binary/Octal/Decimal/Hex base. OR/XOR/AND/NOT and MOD Functions
General Functions : Clear Entry, All Clear, Sign Change
Memory Functions : Memory In/Memory Recall/Memory Plus/Memory Minus/Memory Clear
Parentheses : ()
Precedence : Lower → Higher "1: OR 2: XOR 3: AND 4: +, - 5: /, *, MOD 6: x^y 7: NOT 8: f(x)"
Pencil key/Shift key to switch function
Copy to clipboard/Paste from clipboard
User Theme background
Support instant screen size change
Support multi language
Maping key text on button

cCalcPro (For Nokia E61 only) :

http://home.pacific.net.sg/~welic/cCalc.html

Download here 3rd Edition : cCalc_S60_3rd_111.sis
http://home.pacific.net.sg/~welic/cCalc_S60_3rd_111.sis

Download here 3rd Edition, cCalcPro (For Nokia E61 only): cCalcPro_S60_3rd_110.sis
http://home.pacific.net.sg/~welic/cCalcPro_S60_3rd_110.sis

fring™ is a mobile internet service & community that enables you to access & interact with your social networks on-the-go, make free calls and live chat with all your fring, Skype®, MSN® Messenger, Google Talk™, ICQ, SIP, Twitter, Yahoo!™ and AIM®* friends using your handset’s internet connection rather than costly cellular airtime minutes.

Bringing PC-benefits to the mobile, fring will empower you with mobility and availability as never before, integrating all contacts in to one, searchable buddy list, allowing you to see who’s online before dialing with contact availability indicators, engage in multiple conversations simultaneously, send & receive files and more.

You can even make affordable local and international calls to landline and regular cellular numbers using your SkypeOut/SkypeIn account or almost any internet voice service (SIP) such as SIPNET, EuteliaVoIP, VoIPVoIP and VoIPTalk, even from non-SIP enabled handsets.

What’s more, fring will automatically log you in to WiFi hotspots that you’ve previously logged into, so you can save time and hassle without having to configure your WiFi access points each time you enter a WiFi hotspot whether it be your home, office, or favourite coffee shop, and save even more on calls & chats to your friends, as calls among fringsters and your online communities are 100% free when using your existing WiFi account.

As easy to download as a ringtone and simple to install and use, fring is PC-independent and does not require any dedicated hardware or airtime - all you need to use fring is a supported handset with internet connectivity and an internet data package or a WiFi account.

View fring features:
 
  take all IM buddies mobile and view them from one, integrated contact list
 
  free calls
 
  live chat instead of SMS
 
  call landlines and regular cellular contacts using SkypeOut or SIP
 
  view call history
 
  invite friends to fring 
 
  send & receive files
 
  choose incoming call and message tones 
 
  auto-roam in and out of WiFi hotspots 

* fring is compatible with Symbian 8, 9.1, 9.2, Windows Mobile 5 & 6 and UIQ handsets.
** Voice for Yahoo!TM and AIM® is still not enabled.

what is fring? :  http://www.fring.com/fring_is/what_is_fring/

download fring:  http://www.fring.com/download/

Minimum requirements
1. Applicable 3G or Wi-Fi Symbian 8 or 9, Windows Mobile 5 or 6 and UIQ handsets (see visual list) with 3G/GPRS/Wi-Fi network coverage.
2. If using over 3G/GPRS networks, a data plan allowing you to surf the Internet from your mobile handset.
3. 200-375kb of available space on memory card or phone.