Implantable stimulation systems and method for nerve and/or muscle stimulation applications comprises two functional modules which are, i) a programmable pulse generator module, and ii) a stimulus-receiver module. The stimulus-receiver module is designed to provide stimulation/blocking pulses with an external stimulator. An external device acts as a programmer and as an external stimulator. The system uses implantable power source until stable external power is available. A power select circuitry switches between implanted power source and external power source, when its available. Stimulation/blocking to nerve or muscle tissue may be provided using implantable pulse generator, or via an external stimulator which is inductively coupled to the stimulus-receiver portion of the implanted system. Numerous applications of the system include, spinal cord stimulation to provide therapy for intractable pain and refractory angina; occipital nerve stimulation to provide therapy for occipital neuralgia and transformed migraine; afferent vagus nerve modulation to provide therapy for a host of neurological and neuropsychiatric disorders such as epilepsy, depression, Parkinson's disease, bulemia, anxiety/obsessive compulsive disorders, Alzheimer's disease, autism, and neurogenic pain; efferent vagus nerve stimulation for rate control in atrial fibrillation, and to provide therapy for congestive heart failure; gastric nerves or gastric wall stimulation to provide therapy for obesity; sacral nerve stimulation to provide therapy for urinary urge incontinence; deep brain stimulation to provide therapy for Parkinson's disease, and other neurological and neuropsychiatric disorders; cavernous nerve stimulation to provide therapy for erectile dysfunction.