When it comes to small claims court, yes, definitely. Small claims court was designed to be accessible to nonlawyers. In a regular, more formal courtroom, sometimes it's also a good idea to represent yourself. Hiring a lawyer is almost always unaffordable for disputes that involve less than $25,000 and often unaffordable for disputes in the $50,000-$100,000 range. In these cases, representing yourself may be your only reasonable option.
For complete, up-to-date information on court rules and procedures, see Represent Yourself in Court: How to Prepare & Try a Winning Case, by Paul Bergman and Sara J. Berman (Nolo).