TopWeddingSites.com has many sample father of the groom speeches and toasts for use as templates or starting points. The speeches and toasts are of varying lengths and are easily tailored to match personal speaking styles or different comfort levels in public speaking.
Myfatherofthegroomspeech.com is also full of tips and ideas on writing a father of the groom speech, based on one father's personal experience. The Man Registry suggests offering a prayer, if appropriate, so consider whether a prayer or a blessing from the father of the groom is the best way to address the newlyweds. Alternatively, a brief speech or a toast can benefit from incorporating a meaningful quote; try a resource such as BrainyQuote to search for an inspirational quote from a beloved author or celebrity.