Ali Jahanshiri's Personal WebsiteVerb conjugator and concise, but extensive grammar resource.
A real gem. In addition to many other things, this contains one of the most concise, well-organized guides to Persian grammar you'll find, and a verb conjugator that works with both Persian script as well as roman transcription.
It was a great help to me when I was coding the grammar-parser of Farsi.school, and also my inspiration to start the page you are reading right now.
Ali is taking Bitcoin-donations, and if you find is site useful, I encourage you to support him.
Cooljugator PersianConjugation Tables for Persian Verbs
This will give you the conjugation table for a Persian verb. Conveniently, it lets you input a word in any form, including in a transliterated shape. Pretty neat: You can also have it display the English translation for every individual form.
My Persian CornerBlog on Persian Food and Culture
Strictly speaking, this is not specifically for language learners (though there is a decent amount of such content there as well, including idioms and Persian music with translations). But beyond that, it deserves a mention simply because of the great insights into Iran and it's society and culture; I like to read it when I have some down time, and before I know it, I have this urge to work even harder to learn the language.