Something that might seem obvious but bears repeating – make access to information about giving to your institution easy, and give as much information as possible where applicable.
University of California, San Diego has a great-looking “banner” graphic for giving at the top of each page – this carries with the top site navigation throughout the site (but is actually not part of the site navigation system) without manual manipulation on each page. It’s noticeable without being obtrusive, and site visitors will always know where to go when they want to access giving information.
Don’t forget to take advantage of other opportunities to weave online giving into automated processes or places where traffic is high.
Reunion or other event registrations can bring in site visitors who might not come to your site any other time. Strake Jesuit College Preparatory includes information and giving fields for a Class Gift on the last tab of the Reunion registration form. (They also make it very clear that giving is not necessary to complete the registration process!) At last count, 30% of registrants were making a gift.
On every page
On event registration forms