Yerushalmi Ki-fshuto by Saul Lieberman. Covers Shabbath, Pesachim and Eruvin. Second edition from JTS Schocken Press.
Tosefta Ki-fshutah by Saul Lieberman. The author often embeds commentaries on the Jerusalem Talmud in this work on the Tosefta.
Yerushalmi Nezikin edited by Eliezer S. Rosenthal with introduction and commentary by Saul Lieberman. The text based on the Ascrorial manuscript often preserves alternative textual traditions to that of the standard Yerushalmi editions
Hiddushim u-ferushim – by Levi Ginzburg on part of Berakhoth. (Second edition in preparation.) Available in pdf format from JTS Schocken Press.
A concordance of Amoraic Expressions, phrases and Terms in the Yerushalmi, Moshe Assis.
The Terminology of the Yerushalmi: Principle Terms , Leib Moscovitz.
A Concordance of Palestinian Aramaic, Michael Sokoloff.
The Comprehensive Aramaic Lexicon (http://cal.huc.edu/). Contains all Aramaic texts discoverd until this day. The definitions of words in the text of the Jerusalem Talmud can be conveniently pulled up by clicking on them (Source: Sokoloff)
Jerusalem Talmud Redaction Blog (http://talmud-yerushalmi-redaction.blogspot.com/) by Michael Linetsky. A work in progress containing observations of redactional significance on each sugya.
Parallel Sugyoth by Moshe Assis. (Doctoral Disseration). Discusses parallel sugyoth and their original place of composition.