Here is a selection of calls I've found on the excellent xeno-canto website of the type of vocalisations I've heard species give while migrating. If you've never given a vismig session a go before listening to these, and remembering them, should give you a great start.
Reed Bunting (both call types)
Song Thrush (the first 'tik' call)
Pied Wagtail (actually White Wag, but essentially the same)