All singing and dancing LRC applet.

You can control all basic values L, R, C , V0 [peak V] &  f [omega].

The applet will display the voltage traces for resistor, inductor and capacitor, plus the current in the circuit. It also calculates the reactances and impedance [showing the vector sum as well] showing them as phasors for good measure.

All you need to know.

http://www.ngsir.netfirms.com/englishhtm/RLC.htm

Simple applet showing Impedance v frequency for an LCR circuit.

Slider controls for R, L, C,& f

http://mysite.verizon.net/vzeoacw1/impedance.html