Another player race! Another wacky picture!
Literally the default PC race. Unique feats and PrC's (hint hint shadowcraft mage, hint hint blade bravo) make this a good choice for many builds, so the +0 LA shouldn't have to be explained.
If it weren't for whisper gnomes, I bet those would be seeing a lot more play. Continous Pass Without Trace, an extra hide bonus, extra bonuses against common foes, and Speak With Animals has a few types switched around and becomes at-will; all this at barely any cost compared to regular gnomes. Even so, +0 LA is plenty.
Svirfneblin, or deep gnomes, are different from their surface cousins in a number of notable ways. The ability scores are almost completely changed (though stay roughly equal in power), SR has been added, SLA's with a huge bonus to the save DC are tacked on, long-range darkvision is now usable... In addition, a large number of granular bonuses are gained, as well as blanket bonuses to AC and saving throws. Svirfneblin also have a number of race-exclusive feats (Summon Earth Elemental is pretty nifty) while still qualifying for all regular gnome goodies.
The official LA of +3 is (obviously) far too much. +1 is probably a better assignment, though they will probably be on the strong side of that LA.