Diabetic Cats in Need accepts PayPal donations at firstname.lastname@example.org. Use the "Personal" tab and the radio button for "gift" to avoid fees on cash and checking donations. If you use a credit card, you can choose to pay the fee to maximize your donation to the fund.
If you don't want to go through that effort, this is the Paypal donate button for contributions to help the DKA Kitty in TX. PayPal will charge DCIN a fee for this.