For a limited time, two JetBlue credit cards are boosting their possible sign-up bonuses to dizzying heights, if you apply in an eligible way and are willing to spend more. According to Barclays, the issuer of JetBlue’s cards, an offer to earn 100,000 bonus JetBlue TrueBlue points will be available for the following cards if... Erin Hurd is a writer at NerdWallet.