HT Games
Infinite Experience
Go to Big Town, located northwest of Springvale Elementary. Talk to Bittercup and ask about her dating triumphs, then talk to Pappy about how he came to Big Town. This will start a Speech challenge. If you succeed, you will get six experience points and the option to retry the challenge. You'll be able to retry an infinite number times whether your fail or succeed, and you will get experience for each success.
Infinite Caps and Supplies
This will work with any merchant in the game, but you will need two of the same weapon, one in good condition and one in bad condition. Sell the merchant both the weapons, and buy back the cheap one to sell it back. Every other time you do this, the merchant will give the weapon in good condition for the price of the one in bad condition. If you buy supplies before taking advantage of the merchant glitch, you can clear out the merchant's inventory and get all your caps back.
Easy Skill Bonuses
This will work with any speech, hacking, lockpicking or pickpocketing skill challenge. Before attempting any of these challenges, save the game. If you fail the challenge, reload the game. Repeat until you succeed, and you'll never lose an opportunity to gain a skill bonus.