The company says it hasn't yet turned a profit, CEO Eric Liu said, but he hopes police departments that currently get its service for free will later sign up for paid premium services and upgrades, such as a secured anonymous tip service through the Web.

MSN: Police embrace emerging social media tool

Why would I leave a big tip on clearly lackluster service?

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Lew began his government service in the 1980s as an aide to House Speaker Tip O'Neill.

NPR: Senate Confirms Lew As Treasury Secretary

Tip the concierge if he or she provides you with a special service.

FORBES: Plane Jane: Travel For Business Like A Pro

Bellon got a tip from an investment banker that Marriott International wanted to spin off its service business to focus on hotels.

FORBES: At your service

This is just the tip of the iceberg for Nintendo TVii, which will be a free service when it launches in the United States and Canada.

FORBES: Has Nintendo Beat Apple to iTV?

The novels still read thrillingly today (here's a tip: the best of them is "On Her Majesty's Secret Service"), but there is no question that when the movies came along, they overshadowed Fleming's ink-on-paper volumes.

CNN: James Bond on Her Majesty's Secret Service

If you take a taxi, tip the driver 15-20% of the bill, plus a few extra dollars for extra service such as helping you with a heavy bag.

FORBES: Plane Jane: Travel For Business Like A Pro

Specifically, to what extent can the quality of service on second and subsequent visits be expected to vary based on the size of the tip on the first visit?

ECONOMIST: Mexican stand-off

The ombudsman provides an appeals service when complaints made directly to financial firms are turned down, so its workload is simply the tip of the iceberg.

BBC: PPI complaints at 11,000 a week, says ombudsman