As BBlake said Ranger's Spell list is limited due to the Rangers main focus not being spells.
Assuming you are not wanting to multi class the options below are useful.
Thanks to Rob and GoBLiN for showing me some other options. I have added them below
Two World Magic: Lets you add one 0-level spell from a class that is not your own to your spell list. If your class cannot cast 0 level spells it adds it as a level 1 spell.
Nature Magic: Grants the spell Know Direction as a spell like ability as well as one other Druid Orison cast-able once per day with your Character Level as Caster Level.
Arcane Talent: Only available to Elves, Half-Elves, and Gnomes. Allows the character to select one 0 level spell from the sorcerer/wizard spell list to cast 3 times a day as a spell-like ability with Character Level as Caster Level.
A Ranger does not use a spellbook like a wizard does so you would not be able to copy anything into a spellbook. A Ranger is more like the cleric where he meditates and receives his spells from a higher power. In the case of the Ranger this is his bond with nature.
Below are some 3.5 feats that you might ask your DM if he/she would allow.
Mother Cyst: From Libre Mortis comes the creepy way to get spells. You grow a cyst and can add necrotic spells to your spell list.
Initiate Feats: This is not a specific feat but is a list of feats from 3.5 that grant various abilities. As the name suggests you become an Initiate and gain access to a limited amount of something depending on the feat.