A third pronunciation, /eɪ/ ("long a", as in face), exists for ae in words taken from Latin, but it's a bit harder to explain, so I've postponed my discussion of it to the end of this answer. Also, I think it's not very common for words pronounced with /eɪ/ to be written with the ligature æ. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.