Let her cry herself to sleep? How cruel!
I would suggest an earlier bed time as well, with a set routine like tigwig has suggested.
I am what is known as an attachment parenter. I have never allowed my children to cry themselves to sleep and in fact, research is showing that it could cause long term damage
http://observer.guardian.co.uk/uk_news/story/0 ,6903,1345420,00.html
http://www.post-gazette.com/pg/05319/606752.st m
The second link explains that Dr Ferber, the founder of crying our or controlled crying has now retracted his advice as being wrong.
If this presents itself as a long term 'problem' can I suggest the No Cry Sleep Solution? You can probably get a copy of it in the library but it suggest many different and gentle methods of sleep training
Best of luck