Tools
Emission calculator
You may play around with DIFFICULTY_TARGET and EMISSION_SPEED_FACTOR parameters and check how your coin's emission will look like compared to Bitcoin. The graph below projects emission percentage for the first 30 years.
Prefix generator
You may choose a letter (in some cases several letters) all the coin's public addresses will start with. Since the rules for address prefixes are nontrivial you may use the prefix generator tool below.