Addgene is a non-profit organization dedicated to making it easier for scientists to share plasmids. Adgene distributes high-quality published plasmids on behalf of scientists.
http://www.addgene.org
Plasmid Information Database (PlasmID) is a central repository for plasmid clone collections and distribution as part of the DF/HCC DNA Resource Core based at the Harvard Institute of Proteomics (HIP).
http://plasmid.med.harvard.edu/PLASMID/
A collection of cloning vectors of Escherichia coli is kept at the National Institute of Genetics as a resource for the biological research community.
http://www.shigen.nig.ac.jp/ecoli/strain/cvector/cvectorExplanation.jsp
A place to find a few common plasmid maps
http://www.neb.com/nebecomm/tech_reference/restriction_enzymes/dna_sequences_maps.asp
The Molecular Biology Vector Sequence Database
http://life.nthu.edu.tw/~g854202/Vecdtb.html
VecScreen is a system for quickly identifying segments of a nucleic acid sequence that may be of vector origin developped by the NCBI
http://www.ncbi.nlm.nih.gov/VecScreen/VecScreen.html
EBI tool is based on NCBI BLAST2 and uses the latest implementation of the BLAST algorithm and a special sequence databank known as EMVEC. EMVEC is an extraction of sequences from the SYNthetic division of EMBL containing more than 2000 sequences commonly used in cloning and sequencing experiments.
http://www.ebi.ac.uk/Tools/sss/ncbiblast/vectors.html