There's a few I2Psites that track other I2Psites (and share hosts.txt files). You can subscribe to these (attaching *.i2p domains to their respective long base32 links). By default stats.i2p and a few others are in your address book.
There used to be some I2P-only search engines but I'm not sure if they exist anymore.
There used to be some I2P-only search engines but I'm not sure if they exist anymore.