Cicero Sources

Primary Sources: An index to online texts and translations of Cicero's works
Plutarch's Life of Cicero (the Perrin translation)
Plutarch's Comparison between Demosthenes and Cicero (the Dryden translation)
Cassius Dio's History of Rome. Books 36-47 set Cicero's career against the general history of his times(Carey translation).
Appian's Civil Wars covers much the same period.
A good summary and analysis of Cicero's speech defending Sextus Roscius.
The surviving parts of Cicero's election campaign speech against Catiline and Antonius with comments by Asconius
Sallust's Conspiracy of Catiline
Appian's account of Catiline's conspiracy can be found in his Civil Wars II.2-8 and Dio Cassius' is at his Roman History Book XXXVII.29-42
Secondary Sources The Cicero Hompeage This website has links to some texts in Latin, and a chronology and bibliography. Only useful for those who can read Latin or have access to a university library.
The Internet Encyclopedia of Philosophy's article on Cicero has a good summary of his life, and discussion on various philosophical schools of thought of the time and Cicero's attitudes to them (with internal links to more detailed discussions).
[URL = <http://heraklia.fws1.com/contemporaries/cicero/index.html >]A good overview of Cicero's life in the Caesar's Contemporaries series.

See the articles on Judex and Actio from Smith's Dictionary for a description of legal procedure and juries. Warning: quite technical
A good overview of Catiline's life
The entry from Platner and Ashby's Topographical Dictionary of Ancient Rome for Cicero's house on the Palatine.
A quick rundown of the history and geography of Cilicia. Includes a picture of a bust of Cicero.
This translation of Plutarch's Life of Cicero has a picture of what is reputed to be Cicero's tomb.
The above is a slightly adapted version of four articles previously published at Suite 101 between December 2003 and February 2004.