WebLogo is a web based application designed to make the generation of sequence logos as easy and painless as possible.
http://weblogo.berkeley.edu/
Weblogo server
http://weblogo.berkeley.edu/logo.cgi
RNA Structure Logo
http://www.cbs.dtu.dk/~gorodkin/appl/slogo.html
Protein Sequence Logos using Relative Entropy
http://www.cbs.dtu.dk/~gorodkin/appl/plogo.html
SeqLogo generate sequences logos from amino acid sequence alignment. Sequences logos are useful tools to visualyze sequence pattenrs and represent a more informative alternative to consesus sequence.
http://bio.dfci.harvard.edu/Tools/seqlogo.html
The CorreLogo server generates for a given RNA or DNA sequence alignment a three-dimensional representation in VRML format and JavaView JVX format.
http://correlogo.abcc.ncifcrf.gov/