Available on both Twitter and Facebook, one of Amex‘s latest social media deals should have widespread appeal: Get a one-time $5 credit the next time you spend at least $25 at a Shell gas station.

To participate through Twitter:

1. Sync your Amex with Twitter (see instructions here)
2. Tweet using hashtag #AmexShell
3. After you’ve received an “@ reply” message from @amexsync stating that this offer has been added to your card (you can see this message on the “@ Connect” page under “Mentions”), use your synced Amex to make a single purchase of $25 or more at Shell by 7/31/12.

Full terms of the offer can be found here.

Alternatively, you can sign up for this offer through Facebook and Amex’s “Link, Like, Love” app:

1. Sync your Amex with Facebook by visiting www.facebook.com/americanexpress, going to the “Link > Like > Love” page and launching the app. (Note: You will need to grant the app access to your profile.)
2. Once your card is synced, the “Link > Like > Love” app should show the Shell offer. Click the “Add to Card” button.
3. Spend at least $25 by 7/31/12 at Shell with your synced Amex to redeem the offer

While you’re in the “Link > Like > Love” app, you should also notice other offers, including many from local businesses. A few of the more notable national offers currently include:

Merchant	Offer	Expiration date
Movietickets.com	Spend $20 or more, get $10 back	7/31/12
Ticketmaster.com	Spend $75 or more, get $25 back	7/31/12
Foot Locker	Spend $100 or more, get $20 back	8/31/12

Update 7/4:
Some recently added Twitter deals:

Merchant	Discount	Hashtag	Dates Valid
Provincetown, MA	Get $20 back after spending $20 in Provincetown, MA	#AmexPtown	7/1/12-8/18/12
Ticketmaster.com	Get $25 back after spending $75	#AmexTM25	7/3/12-7/31/12
Frontrunner	Get $20 back after spending $100	#AmexFrontrunner	7/2/12-10/2/12