Both this builds are alternative nidalee builds for people who just love the champion, and want to play with her in every role. Personaly i like playing tanks, and thats why i have tried different tank builds on nidalee. Because nidalee is my main, i have found of different ways to play one of the most complicated champions in this game. Why early health items and also late game tank? Because Nidalee is a champion with high base dmg on her abilities, low cds, and rly bad endgame scale with ap. Personaly i like buying health items early to get tanky. One you have your ulti in lvl 6, you are the king of the game. Health gives you a big burst early, while ap gives you better heal and just a little bonus dmg. Tanknidalee is very good at "getting behind enemy lines". She can run trough in teamfights, and jump on the other team's carries. with shen and low cds, she has good dmg in catform. These are the tank builds:

Tank Nidalee for solo top / (troll) bot: In this build i go for leviathan. I dont know if thats smart or good for the team, but i have this habbit of kilsstealing with my ulti "q" in normal games, and with your heal and long range spear, its easy to get assists, and then also 20 stacks. I think Leviathan is bad for a snowball item, unless you get 20 stacks. so if your lane fails, you should probably go for other early health items.
Items for top/bot nida: follow build over, but note: u should choose the boots u like by yourself. Look at the enemy team. if they ahve a lot of ad dmg, buy armor boots, and if they got a lot of stuns, buy tanacity boots. Nidalee can get killed easy if stunned or snared, but if shes not, she can just jump away over walls. thats why i normally buy tanacity boots. Trinity is not a "must have" item. Shen is good early, and if you want bonus damage late game you should go for trinity. But if your team fails, you should go for a thornmail. with 4000+ hp that is a rly good item for you + you have heals and a lot of health regen, so that your thornmail will deal almost 1500-2000 bonus dmg in total if you die.

Jungle nidalee: My favourite build. People say that Nidalee cant jungle. That is totaly ********. Nidalee is a slow jungler before lvl 6, but she actually ganks very well, even before lvl 6. Ranged attacks + redbuff + teammates is a good combo, and you can pick up a kill easy at lvl 3/4 if the other team push. when you hit lvl 6 and get mandreds jungle is easy. With your ulti "w" and tank items, you can run around in other teams jungle and steal buffs. If u get attacked, and can not kill him 1v1, just jump over some walls (http://www.youtube.com/watch?v=p_3Lf8zzWRY). She is also good at stealing buffs. with a 3 sec cd on ulti "w" you can jump over baron and dragon walls (see video), smite, and jump back. because your tanky, they wont manage to kill you. However, as i said, nidalee is a slow ealry jungler, and she realy needs bluebuff. With bluebuff, nidalee can stay in jungle with full health all the time, and she can heal allies and trap the other team's jungle. Its nice to trap their red and blue buff. Nidalee is the king of the jungle because she can jump, trap, heal, move fast and slow with red/ranged.
The 2 last items i added are not always the best. For example, you should maybe choose Force of nature instead of banshee if u want to get more tanky. Thornmail is also a good item with warmogs, and wriggle can also be a good item endgame.
When you jungle you should start with cloth armor and 5 pots. You dont need all the pots, but i like to have some extra, so you can always be prepared to gank. Start at bluebuff, then go all the way down to red. Rememer to use your heal all the time, to get health and atackspeed. Always trap the big creeps. You can gank after red, or you can go to dubble golems, and then gank.