Many people may consider wearing earplugs as 'uncool', but in very loud environments (above 90dB sound pressure), they are very much recommended or even required (for instance in certain jobs) in order to protect the hearing (for a corresponding chart with examples of noise levels and maximum exposure times without hearing protection see http://www.gcaudio.com/resources/howtos/loudness.html).
So by all means, ear plugs or other hearing protection should generally be used to protect the hearing in those loud environments (see for instance http://www.earplugs.de for a wide variety of earplugs (you may find some of these cheaper on Ebay or Amazon). Otherwise the risk of hearing damage and/or tinnitus can become very real.

Hearing protection is particularly important if one has tinnitus already, as any kind of noise can aggravate the condition, especially in the early stages (the first 6 months). Many people suffering from tinnitus have actually at some stage an over-sensitivity to virtually all sounds (hyperacusis), and in these cases it may even be beneficial to use earplugs in more normal environments as well (for instance when using the vacuum cleaner at home). The drawback with using earplugs with tinnitus is that, due to the external background noises being reduced, the tinnitus appears as even more prominent, which could cause even more emotional upset for some people. However, for others it is more important to have the feeling of being safe from a further aggravation of their condition due to sounds (just being anxious about a possible aggravation can aggravate the condition by itself). I would recommend that everybody handles this as it is best for the well-being of the person. This obviously can only be found from the individual experience, and it may therefore take some time to figure out the right strategy here.

Thomas