Having just ordered my new version of HymnQuest I thought I'd give it a quick plug and explain why I am always happy to pay for my own copy.
Firstly it covers hundreds of hymn and song books from, ooh, Hymns Ancient and Prehistoric via Lightbulb Changing Songs 2010 to Plainchant for Beginners - whatever your style or wherever you are going you can be pretty sure it'll be there.
Secondly it has loads of dead easy to use cheats for busy worship leaders - you can pick items based on keywords, themes, lectionary date, Bible chapter or book. So if your want hymns/songs with the word 'dandelion,' the phrase 'God is spiffing,' relating to Leviticus 15:12, for Year B Sixth after Trinity or on the theme of 'deep sea fishermen' you can find them at the drop of a hat. OK, maybe not my exact examples, but you get the idea.
Thirdly, if you buy the copyright licence users edition (CLUE), you can export straight to projection software - and even in the basic version loads of things can be exported to word processing or projection software with a couple of clicks.
Fourthly you can check tunes - the set ones can be heard (in part) for most things and via the metrical search you can find alternatives. Not so easy with the latest 'irreg and refrain' but great for traditional style hymns in CM, LM, DCM and so forth.
Fifthly it's cheap! The CLUE version is £40 a year and the standard version (which I have) a mere £20 to upgrade from 2010 to 2011. Given the cost of a typical song/hymn book in music edition you get your money back instantly with Hymn Quest. It doesn't stop me buying more books - but at least I can be more confident I'm not buying yet another copy of what boils down to 'Zillions of Songs You Already Knew.' Most of the Hymn Quest stuff appears in loads of books - and that's great as it makes it easier to find stuff that will be known in ecumenical settings and/or to find 'legal' variants of words.
Many if not most readers will already know of HQ, but if you don't, may I suggest you consider trying it out - at £40 it's less than £1 a week for churches with CCL/Calamus and it just might lead you to some new and interesting stuff from surprising stables.