on-line folkish search resources (Mr Red found & sometimes found useful) fill window
Catalogues

Bodleain Library
choose OLIS & the combined search which includes sheet music. Full lyrics cost money.

British Library
Includes (mostly) attributed song references ie sheet music. Full lyrics cost money.
US Library of Congress
not so good for UK or Australian/NZ based songs,
 
South West UK Library Search
more for me or people who use the libraries in the south West of England
Gutenberg Project
more about books but includes music.
Music Hall Hiss Boo Co
More a point of contact.
  Micheal Kilgarrif.
an authority
Music Hall Soc
good for follow-on sites
 
Music Free Sheet Music (ABC)

Notation Machine

trebleSearch
aggregator site
Leevy Sheet Music
commercial. sales only
ABC tunefinder
excellent for trad tunes/lyrics. in a variety of formats.

8notes.com
large list of tunes. Well worth a look

Chris Walshaw's ABC site (he did invent it after all search for tunes tunes page Sea Songs
Research folkOpedia- has just started. Nascent online Folk encyclopedia. Mr Red has contributed.  
Lyrics Digital Tradition (Mudcat) search both the Forum and the Digital Tradition for lyrics/tunes/background. songs recorded at the Eel's Foot, Suffolk, 1937  
Lists of sites Martin Nail
lots of useful links, some seen here.
Bob Tabenber
keen dancer but eclectic folkie

Trad Song home
(Martin Graebe)
Their ListsLibrary

South Riding Folk
more copious links.
reflecting MD's interests.
 
Forums Mudcat Cafe
beware of opinions - sometimes they are supposition strongly put - but generally very helpful given that. Beware the unwritten ettiquette - some delight in telling you after transgression.

Tradsong Forum
(on Yahoo)

Seems fairly comprehensive.

BBC war
related opinions on wars.
(because I have questions about military songs that's why)

E-ceilidh UK (e-mail)
e-mail forum, if you want answers - ask. Beware - topic is narrow focus,ceilidh trivia, ceilidh steps and ceilidh tunes only.   No Sq*res, C*ntr*, Fr*nch, C*j*n (or else!).OR Zesty C*ntr*

try Allceilidh instead - (less narrow)