I've modified them a bit, for improved coolness.
Basically, you normally cease to get familiar benefits after level 15. Sure, its Int and natural armor continue progressing, as well as its HD, hp, and other level-related things. But that's all. And you also get nothing nifty at level 9.
So, here's the modified table I use:
Code:
[b] Nat
ML-CR Armr Int Special[/b]
0 +0 5 Empathic link
1 +1 6 Share spells, imp. evasion
3 +2 7 Deliver touch spells
5 +3 8 Speak with master
7 +4 9 Speak with related animals
9 +5 10 Soulshelter
11 +6 11 Spell resistance
13 +7 12 Familiar's eyes 1/day
15 +8 13 Familiar's eyes 3/day
17 +9 14 Familiar's eyes 5/day
19 +10 15 Familiar's eyes at will
You do not need Improved Familiar. Like for Mounts or Animal Companions, you can get a better familiar at the cost of you master level. So, instead of just your master level (ML), you use your master level minus the base creature's CR.
The familiar doesn't give you Alertness. Instead, it is considered to be constantly using the Aid Another action to help you on your spot and listen checks, taking 10. It can only do that if is close enough from you for its perceptions to be meaningful for you, and it needs to do nothing else. But in effect, it does work like granting you alertness when on the same square as you. It's just worded differently, so as to make sure that 1°) it doesn't fulfill an Alertness prerequisite and 2°) it stacks with the Alertness feat if the spellcaster has it.
Soulshelter: If the master dies, his soul can take hold within the familiar instead of going wherever souls go. As a result, the familiar stays a full-fledged familiar (instead of losing two master levels as is IIRC the normal rule). Time passing while the master's soul is sheltered in the familiar doesn't count for the purpose of spells like
raise dead. Furthermore, once per day, the master may possess his familiar for 10 minutes/level. During possession, he can cast spells (better have the Sudden Still or Still Spell feat, though, for paws aren't exactly appropriate for somatic components) and speak normally, with his own voice.
Familiar's eyes: instead of being able to scry on the familiar, the master can see through the eyes (and hear through the ears, etc.) of his familiar, for 1 minute/level, a certain number of time per day.