I also found the word doulos in these verses (this is by no means an exhaustive list). I am typing from the New International Version, though found the word from Strong's Bible Dictionary and the KJV Bible.
Matthew 10:24-25 - [color=FF0000]A student is not above his teacher, nor a servant above his master. Is is enough for the student to be like his teacher, and the servant like his master.[/color] (See also John 13:16)
Matthew 18:21-35 - (The parable of the unmerciful servant)
Matthew 20:26-28 - [color=FF0000]Not so with you. Instead, whoever wants to be great among you must be your servant, and whoever wants to be first must be your slave -- just as the Son of Man did not come to be served, but to serve, and to give His life as a ransom for many.[/color]
Matthew 24:45-51 - (How will the Lord find His servants when He returns? See also Luke 12:42-48, and the [url=https://www.sermonindex.net/modules/newbb/viewtopic.php?topic_id=478&forum=38&10]"midnight" thread[/url].)
Matthew 25:21, 23 - [color=FF0000]"His master replied, 'Well done, good and faithful servant!...'"[/color] (from the parable of the talents; see also Luke 19:17)
Mark 10:44 - [color=FF0000]...and whoever wants to be first must be slave of all.[/color]
Mark 12:1-10 and Luke 20:9-18 - (The parable of the tenants)
Luke 2:29 - "Sovereign Lord, as you have promised, you now dismiss your servant in peace...." (Simeon speaking, praising God for Jesus)
Luke 14:15-25 - (The parable of the great banquet)
John 8:34 - Jesus replied, [color=FF0000]"I tell you the truth, everyone who sins is a slave to sin."[/color]
John 15:15 - [color=FF0000]I no longer call you servants, because a servant does not know his master's business. Instead, I have called you friends, for everything that I learned from my Father I have made known to you.[/color]
Romans 1:1 - Of course. :-P (Also see Titus 1:1, James 1:1, 2 Peter 1:1, Jude 1, and Revelation 1:1)
1 Corinthians 7:21-22 - Were you a slave when you were called? Don't let it trouble you -- although if you can gain your freedom, do so. For he who was a slave when he was called by the Lord is the Lord's freedman; similarily, he who was a free man when he was called is Christ's slave.
1 Corinthians 9:19 - Though I am free and belong to no man, I make myself a slave [douloō] to everyone, to win as many as possible.
Galatians 1:10 - Am I now trying to win the approval of men, or of God? Or am I trying to please men? If I were still trying to please men, I would not be a servant of Christ.
Galatians 4:7 - So you are no longer a slave, but a son; and since you are a son, God has also made you heir. (See in context of 4:1-7)
Philippians 2:7 - ...but made Himself nothing, taking the very nature of a servant, being made in human likeness. (See previous post, by InTheLight.)
2 Timothy 2:24 - And the Lord's servant must not quarrel; instead, he must be kind to everyone, able to teach, not resentful.
Philemon 16 - (Onesimus)
Revelation 15:3 - (speaking of Moses)