While tithing is seen in the Old Testament, in the New Testament we see a lot of offerings. The idea of offerings tends to be spontaneous givings of money as the Holy Ghosts tells us to.

For example, in places where persecution was high, Christians often sold their land and gave it to the church so that the church members could take care of each other.

Acts 4:34-37 - Neither was there any among them that lacked: for as many as were possessors of lands or houses sold them, and brought the prices of the things that were sold,And laid them down at the apostles' feet: and distribution was made unto every man according as he had need.And Joses, who by the apostles was surnamed Barnabas, (which is, being interpreted, The son of consolation,) a Levite, and of the country of Cyprus,Having land, sold it, and brought the money, and laid it at the apostles' feet.

In countries where people are disowned by family or fired from businesses, some churches have similar practices.

Offerings also include what we give to people who have needs, like money or food. God says that while prayer is good, if we can provide for these people, it is better to give than to merely pray for them or bless them. Giving to the poor is considered a high virtue.

James 2:15-16 - If a brother or sister be naked, and destitute of daily food,And one of you say unto them, Depart in peace, be ye warmed and filled; notwithstanding ye give them not those things which are needful to the body; what doth it profit?

Acts 20:35 - I have shewed you all things, how that so labouring ye ought to support the weak, and to remember the words of the Lord Jesus, how he said, It is more blessed to give than to receive.

Galatians 2:10 - Only [they would] that we should remember the poor; the same which I also was forward to do.

Proverbs 3:27-28 - Withhold not good from them to whom it is due, when it is in the power of thine hand to do it. Say not unto thy neighbour, Go, and come again, and to morrow I will give; when thou hast it by thee.

God says what we give should be because we know God wants us to and with a cheerful, willing attitude.

2 Corinthians 9:7 - Every man according as he purposeth in his heart, [so let him give]; not grudgingly, or of necessity: for God loveth a cheerful giver.