I believe you can legally keep most lizards, small colubrids and other non-prohibited animals. Boas and Pythons are prohibited based on what I can find here, contact your city and county departments to confirm if unsure, they are usually happy to give you the info:

http://library.amlegal.com/nxt/gateway.dll/California/health/article1animals?f=templates$fn=altmain-nf.htm$q=[field%20folio-destination-name:%2751%27]$x=Advanced#JD_51

I copied/pasted:

SEC. 50. PROHIBITION.
No person shall have, keep, maintain or have in his possession or under his control any wild and potentially dangerous animal as defined in Section 51, unless excepted therefrom pursuant to Sections 50 through 66 of this Chapter.

SEC. 51. DEFINITION OF "WILD AND POTENTIALLY DANGEROUS ANIMAL".
II. Class Reptillia
A) Order Squamata
1. Sub-Order Serpentes, all front and rear fanged venomous snakes and all species of the Families Boidae and Pythonidae.
2. Sub-Order Lacertilia, both venomous species of the Family Helodermatidae (Gila monster and Mexican beaded lizard).
B) Order Crocodilia (crocodile and alligator).