#1 STUDYBLUE. I remember loving Studyblue because I absolutely hated the amount of time it took me to write out vocabulary words on flashcards. With Studyblue, all I had to do was type! {Side note: They even give you suggestions from what other users of Studyblue have done}. Now, as a teacher, I love Studyblue even MORE. I can make my students online flashcards, sign them up, and then they have no excuse! It's fun, they can quiz themselves using the flashcards or the quiz. If they get a certain amount wrong, they can go back and quiz themselves on the ones they are having a hard time with!
Conjuguemos does ask for $50 to subscribe to their services, but I would say that it's totally worth it. It definitely beats students half-doing a worksheet of boring conjugations! It makes it somewhat competitive and fun! (They can also do this with vocab, but I like Studyblue better for vocab practice!)