Short answer. Yes. I do this all the time without issue.
In fact, you do not have to search Google very long to see other examples where a period (.), dash (-), underscore (_), etc. are used. There are some characters that have special meaning that you should be aware of.
From this page: http://www.skorks.com/2010/05/what-every-developer-should-know-about-urls/
The list is:
; / ? : @ & = + $ ,
Avoid these and you should generally be fine. As well, when you have the time, the page I linked to is a programmer talking specifically on the topic in question so you may want to read what he has to say.