I deal primarily with custom .net WebForms and MVC based applications, but someone came to me and asked for help with creating a small website for their non-profit organization for which they will need to be able to accept donations.
My preference would be to use a simple CMS, and I have heard of Shopify and the Shop Plugin for WordPress, but they really don't need that level of e-commerce. Basically what I am looking for is some advice for using a simple mini-CMS, be it WordPress, Squarespace, etc, and integrating some method for accepting and keeping track of donations.
My initial thought was to use WordPress and then link to Paypal.
Note: WordPress has grown up since a few years ago. It can easily be used as a full-on CMS serving hundreds of pages based on custom data types.
As far as collecting donations, any ecommerce/shopping cart solution is massive overkill for accepting donations. A PayPal link is definitely the fastest way to go. Here is a step-by-step tutorial on how to do it.
Note: some people do not like PayPal, so consider adding multiple buttons. Here is the Google Checkout version. Or 2co looks like they will support it now (or Real Soon Now).