The Amex Business Gold card was a disappointment when it first came out since it had no signup bonus. But now Amex has made a bonus available through referrals. You can earn 50,000 Membership Rewards points after spending $5,000 within three months. It comes with an annual fee of $295.
This makes the card worth applying now. 50,000 Membership Rewards points are worth at least $700-$800 and the card has more perks which should come in handy. Just keep in mind that you are not eligible for the bonus if you had the old Business Gold Rewards card in the past. That card had a 75K bonus just recently, which is no longer possible as far as I know.
You can find more details about the card on my review.