There's a couple ways I came to my conclusion. "Just you and ___ [are] left to do it now.] In this case, you and I are subjects. I is the nominative (subject) form of the word, so it is correct. Another way of reading is "It is just you and ___ left to do it now." Is is a linking verb, which links with a nominative case subject. Again, I.
A subject pronoun must precede a verb.
Stryfe's first solution is undoubtedly valid. The second solution is much more questionable. The verb to be is in this context known as a "copulative" verb (no sniggers please, this has a technical grammar sense!). Copulative verbs can take either the nominative of accusative form as their object. Do you say "it is I" (rather formal but correct) or "it is me" (less formal and also correct). Thus in the example either "I" or "me" is valid, which probably explains why the vote is so evenly divided.
well if you wrote " Just you and me left to do it now" that wouldnt make much sense but if you wrote " Just you and I left to do it now" you could understand the sentence much easier.
muy buena la pagnica