I just discovered this, maybe its common knowledge but I thought I would share it as I didn't know you could even do this until recently.
This is for US Federal Student Loans. I don't know if this works for private loans.
I recently graduated with a Bachelor degree and I have subsided loans and unsubsidized loans with interest rates ranging from 3.4% - 6.8%.
I just discovered that you can select which loans to send the payment to on the payment website.
Your situation might be different but this works for me with my lender, you might want to call your lender before doing this to make sure it applies as your payment:
When you click "Make A Payment" it gives you two choices: "Pay All Loans" or "Specify Loan Payment Amounts"
If you select "Specify Loan Payment Amounts"
It lists all your loans individually:
*Example*
Loan1 $650/6.8%
Loan2 $300/3.5%
Loan3 $4000/5.8%
You can type in the box next to the loan the amount you want to apply to that loan. I've been able to target the higher interest loans first this way.
Also on the view loan details area, you can click "print all loan details" and it breaks it down as far as the amount for each loan, date, payment amount, interest rate, etc.
*Example*
Loan1 1/1/2009 $650/6.8% Payment Plan:10 years Intrest: $15 Payment $10.25
Loan2 2/2/2009 $300/3.5% Intrest: $3 Payment $5.25
Loan3 3/3/2009 $4000/5.8% Interest: $120 Payment $150.25
Loan4........
Total Principal:$55,000 Total intrest $1500 Total Payments:$750 - Monthly
Whats nice about looking at this, is that it shows the amount, interest charged and monthly payment amount for each of the loans.
I've been able to pay off the smaller high interest loans this way. I've been funneling all my extra money that doesn't go to rent/food/gas/etc into this hoping to pay my loans off as soon as possible and avoid paying lots of interest in the future.
Hope this helps someone.