Very simple, only took me about 45 minutes to make.

Tell me if there are any glitches.

Make sure you've got the C++ runtime files.

Yes, I know it's a console application.

Tell me of any glitches you find.

Download: project2.zip
(make sure you extract it)

Source Code ( you can steal, don't really care )
Code:
#include <iostream.h>
#include <math.h>



void anually(double principal, double rate, double years, double leftover)
{
    cout<<"You have chosen anually."<<endl; 
	cout<<"Final account balance after " <<years<<" years is: "<<principal*pow((1+(rate/100)/1), 1*years)<<endl;
	leftover= principal*pow((1+(rate/100)/1), 1*years);
	cout<<"Interest accrued: "<<leftover - principal<<endl;
}
void semianually(double principal, double rate, double years, double leftover)
{
     cout<<"You have chosen semianually."<<endl;
	cout<<"Final account balance after " <<years<<" years is: "<<principal*pow((1+(rate/100)/2), 2*years)<<endl;
	leftover= principal*pow((1+(rate/100)/2), 2*years);
	cout<<"Interest accrued: "<<leftover - principal<<endl;

}
void quart(double principal, double rate, double years, double leftover)
{
     cout<<"You have chosen quarterly."<<endl;
	cout<<"Final account balance after " <<years<<" years is: "<<principal*pow((1+(rate/100)/4), 4*years)<<endl;
	leftover= principal*pow((1+(rate/100)/4), 4*years);
	cout<<"Interest accrued: "<<leftover - principal<<endl;
}
void month(double principal, double rate, double years, double leftover)
{
     cout<<"You have chosen monthly."<<endl;
	cout<<"Final account balance after " <<years<<" years is: "<<principal*pow((1+(rate/100)/12), 12*years)<<endl;
	leftover= principal*pow((1+(rate/100)/12), 12*years);
	cout<<"Interest accrued: "<<leftover - principal<<endl;
}
void weekly(double principal, double rate, double years, double leftover)
{
     cout<<"You have chosen weekly."<<endl;
	cout<<"Final account balance after " <<years<<" years is: "<<principal*pow((1+(rate/100)/52), 52*years)<<endl;
	leftover= principal*pow((1+(rate/100)/52), 52*years);
	cout<<"Interest accrued: "<<leftover - principal<<endl;
}
void daily(double principal, double rate, double years, double leftover)
{
     cout<<"You have chosen daily."<<endl;
	cout<<"Final account balance after " <<years<<" years is: "<<principal*pow((1+(rate/100)/365), 365*years)<<endl;
	leftover= principal*pow((1+(rate/100)/365), 365*years);
	cout<<"Interest accrued: "<<leftover - principal<<endl;
}
void contin(double principal, double rate, double years, double leftover)
{
     cout<<"You have chosen continuously."<<endl;
     cout<<"Final account balance after "<<years<<" years is: "<<principal*pow(2.71828183,((rate/100)*years))<<endl;
     leftover=principal*pow(2.71828183,((rate/100)*years));
     cout<<"Interest accrued: "<<leftover - principal<<endl;
}
void ntimes(double principal, double rate, double years, double leftover, double nt)
{
     cout<< "Enter number of times compounded per year: ";
     cin>>nt;
     cout<< "Final account balance after "<<years<<" years is: "<<principal*pow((1+(rate/100)/nt), nt*years)<<endl;
     leftover=principal*pow((1+(rate/100)/nt), nt*years);
     cout<<"Interest accrued: "<<leftover - principal<<endl;
}




int main()
{
	double principal, rate, years, op, leftover, nt;
	cout<<"                                Interest Calculator."<<endl;
	cout<<"                                  Made by Robyn :)"<<endl<<endl;
	cout<<"This is a simple program that calculates interest."<<endl;
	cout<<"For the most part, it's self explanitory, just input your values when prompted."<<endl;
	cout<<"Hit enter after you input something to continue to the next step."<<endl;
	cout<<"-------------------------------------------------------------------------------"<<endl;
	cout<<endl;
	while(op!=9)
	{
	cout<<"Enter a starting balance: ";
	cin>>principal;
    	while(principal<1)
    	{
             cout<<"You probably want to start out with at least 1 dollar. Just a guess."<<endl;
             cout<<"So, try again: ";
             cin>>principal;
             cout<<endl;
        }
	cout<<"Enter percent interest rate: ";
	cin>>rate;
        while(rate<.1)
    	{
             cout<<"You probably want to have more than a 0% interest rate. Just a guess"<<endl;
             cout<<"So, try again: ";
             cin>>rate;
             cout<<endl;
        }
	cout<<"Enter number of years in the account: ";
	cin>>years;
	    while(years<.003)
    	{
             cout<<"You probably want to have it for at least a day. Just a suggestion."<<endl;
             cout<<"So, try again: ";
             cin>>years;
             cout<<endl;
        }
	cout<<"Select number of times per year interest is compounded:"<<endl;
	cout<<"	1. Anually"<<endl;
	cout<<"	2. Semianually"<<endl;
	cout<<"	3. Quarterly"<<endl;
	cout<<"	4. Monthly"<<endl;
	cout<<"	5. Weekly"<<endl;
	cout<<"	6. Daily"<<endl;
	cout<<"	7. Continuously"<<endl;
	cout<<"	8. Another amount"<<endl;
	cout<<"        OR"<<endl;
	cout<<"        9. Quit the program"<<endl;
	cout<<"Choice: ";
	cin>>op;
    cout<<endl;
	if(op==1)
	{
		anually(principal, rate, years, leftover);
		cout<<endl;
	}
	else if(op==2)
	{
		semianually(principal, rate, years, leftover);
		cout<<endl;
	}
	else if(op==3)
	{
		quart(principal, rate, years, leftover);
		cout<<endl;
	}
	else if(op==4)
	{
		month(principal, rate, years, leftover);
		cout<<endl;
	}
	else if(op==5)
	{
		weekly(principal, rate, years, leftover);
		cout<<endl;
	}
	else if(op==6)
	{
		daily(principal, rate, years, leftover);
		cout<<endl;
	}
	else if(op==7)
	{
		contin(principal, rate, years, leftover);
		cout<<endl;
	}
    else if(op==8)
	{
		ntimes(principal, rate, years, leftover, nt);
		cout<<endl;
	}
	else if(op<1||op>9)
	{
            cout<<"No, only an option 1-9. The program will now restart."<<endl;
            cout<<endl;
    }
    
	
	system ("PAUSE");
	cout<<endl;
    }
    

    return 0;
}