You definitely have the big ones with MSRP and PPDB.
A few others, grouped by maintainers.
CLiC at the Universitat de Barcelona
Maintain several highly annotated corpora.
These are available from their site, by request/registration.
It is a request they grant with almost no questions asked.
(My experience was that after registering online I had to sent them an email).
P4P (paraphrases for plagiarism detection)
The P4P corpus contains a partition of the plagiarism cases in the PAN-PC-10* corpus manually annotated with the paraphrase phenomena they contain. It is composed of 847 source-plagiarism pairs in English.
This is not the hyperlink from the quote, but unlike that one does go to right address.
These are multi-sentence paraphrases. PAN-PC-10 is a Plagiarism corpus, for context
See Paper: A. Barrón-Cedeño, M. Vila, M. A. Martí, and P. Rosso. 2013. Plagiarism meets paraphrasing: Insights for the next generation in automatic plagiarism detection. Computational Linguistics, 39(4):917-947
MSRP-A (annoated MSRP)
MSRP-A stands for “Microsoft Research Paraphrase” corpus “Annotated”. The MSRP-A corpus contains the positive examples in the MSRP corpus manually annotated with the paraphrase phenomena they contain. It is composed of the 3,900 paraphrase pairs in English.
I believe the annotations are similar to those in P4P; but have not looked so I am uncertain. There is no additionally utility here if you don't want annotations.
See Paper: W. B. Dolan and C. Brockett. 2005. Automatically constructing a corpus of sentential paraphrases. In Proceedings of the Third International Workshop on Paraphrasing (IWP 2005), pages 9-16.
WRPA Relational Paraphrase Acquisition from Wikipedia
WRPA stands for “Relational Paraphrase Acquisition from Wikipedia” corpus. The WRPA corpus contains relational paraphrases extracted by the WRPA system from Wikipedia.
It has several types of relational paraphrases. By which the authors mean to the are paraphrases about a particular relations. Eg paraphrases about people person and their place of birth.
See Paper: Vila, Marta, Horacio Rodríguez, and M. Antònia Martí. "WRPA: A system for relational paraphrase acquisition from Wikipedia." Procesamiento del lenguaje natural 45 (2010): 11-19.
For my own work I required a corpus which had a large number of paraphrases for each meaning. For this I constructed a corpus based on Opinosis.
Opinosis is a highly redundant corpus of opinions -- that did not originally have the paraphrases marked. (I can attest there is not a lot of validation of the accuracy of this corpus, given it was only annotated by one person (being me).)
On same pages also links my own automatically grouped MSRP subcorpus, that is less useful, because it it countains paraphrases you already have got from MSRP.
See Paper: Lyndon White, Roberto Togneri, Wei Liu, and Mohammed Bennamoun, 2015: How Well Sentence Embeddings Capture Meaning, Proceedings of the 20th Australasian Document Computing Symposium