Pronunciation is important. If no one understands what a speaker says, it doesn’t matter how many words or tenses he knows – he can’t communicate. Rarely, though, are students totally incomprehensible; it is usually a matter of fine-tuning certain sounds or just drawing students’ attention to typical problem areas.
Two pronunciation activities I’ve used:
Pronunciation bingo: elicit and then model the correct pronunciation of some set of words – for this activity it should be word pairs (or minimal pairs) that sound similar, for example sheep/ship, teen/tin. Students then draw their own grids and randomly place one word in each box. You read out a selection of words and when someone has a row all marked off, they of course call out “bingo”. They then have to tell you which words they marked off – check not only for correct pronunciation but also for whether they got the right word (when you said “sheep’, that’s what they marked off, not “ship”). This works best if you only read out one of a pair of words (don’t say both “sheep” and “ship” because then you won’t know if the student understood you correctly). For a hodgepodge of commonly mispronounced words (development, vegetable, etc.) you can make a grid on the whiteboard and students work in teams – they choose a box and if a team member correctly pronounces the word, they get the box.
Tongue twisters: see this description of a few activities. While students may not get all the sounds correctly, especially if they are whispering or competing for time, this gives them the opportunity to practice and it does draw their attention to it.