HALO Bolt 58830 mWh Portable Phone Laptop Charger Car Jump Starter with AC Outlet and Car Charger
Works great as a power bank for USB.
Used the AC plug a few times to run a fan at night or grind coffee (for a couple seconds at a time before for the coffee otherwise it trips).
Was dubious about the jump start feature. Went out to mow the yard yesterday for the first time in about 5 weeks, totally dead battery.
About to hook up the charger and remembered this power bank.
Hooked it up, fired up instantly

Got in my Jeep to go work this morning same thing (used car with 13 year-old battery the owner kept trickle charged).
Hadn't driven it at all over my weekend. Grabbed the Bolt and it fired up the Jeep just fine, still shows full charge even though I haven't charged it in months and jumped 2 batteries.
Would highly recommend this or something similar. Took 90 seconds from realizing the battery was dead to driving away.