Here are a series of assessment questionnaires and handouts for Generalized Anxiety Disorder:
GAD, 2 question screen - answering "yes" to either of the two screening questions on this sheet suggests it's worth checking for a diagnosis of full Generalized Anxiety Disorder (GAD) - for example by using the GADQ (see below).
GAD, questionnaire (GADQ) - a simple questionnaire for making a full diagnosis of GAD.
GAD, assessment (GADSS) and scoring - the GAD Severity Scale. Useful, and pays more attention to GAD's associated physical symptoms than the more purely worry-focussed scales that are often used.
GAD, metacognitions (Wells) - GAD assessment scale developed by Wells. Includes measures of safety behaviours and metacognitions.