I don’t consider myself 100% proficient in English grammar by any stretch of the imagination, but I do see a lot of business documents in the form of resumes, status reports, and presentations. Spell checkers will help catch spelling mistakes, but typically don’t catch wrong word usage (Microsoft Word seems to do a better job than most). Here are some examples I have seen recently of people using the incorrect word. Do yourself a favor and use the proper word when communicating with others.  It may not seem like a big deal to you, but the person reading it may think otherwise.

Your vs You’re:

This is a personal pet peeve. A coworker had an email tag-line that stated: “Sometimes your the bug, sometimes your the windshield.” I wanted to tell him he was embarrassing himself with every email he sent, but he eventually selected a new tag-line. “You’re” is simply a contraction of “You Are.” Use “Your” to show possession.
• What is your problem?
• You’re it!

To vs Too vs Two:

Two is a number, Too means also or excessively, and To generally describes the receiver of an action
• Take this to Bob.
• I want to work. (In this case, to is used with a verb)
• I like pizza too (meaning also)
• I like pizza too much (excessively)
• I have two arms.

Lose vs Loose:

• Lose is the opposite of win.
• Loose is the opposite of tight.

A lot vs Alot:

• Alot is not a word!

Compliment vs Complement:

Compliment means to flatter someone. Complement means to accompany or complete.
• I compliment you on your work!
• Your blue tie complements your blue suede shoes.

Regardless vs Irregardless:

• Irregardless is not a word! Use regardless.

Whether vs Weather:

Whether means “this or that.”  Weather is the climate.
• Whether you select option one or two, you’re a winner!
• The weather outside is frightful.

Sight vs Site:

Sight is vision. Site is a place.
• You’re a sight for sore eyes
• This is my website

Its vs It’s:

This one is understandably confusing since it breaks the apostrophe rule for possession. “It’s” is simply a contraction of “it is” or “it has.”  To show possession, use “its.” A good test of this is to substitute the word “his” in place of “its.”  If it makes sense, then use “its” if it doesn’t make sense, use “it’s.”
• It’s my turn. (It is my turn.) (Test: HIS my turn?!??!)
• It’s cold outside. (It is cold outside.)
• The Hummer is known for its fuel consumption.  (Test: The Hummer is known for HIS fuel consumption.)

Waste vs Waist:

Waste means trash or to wrongly use. Waist is a body part.
• Don’t waste your money!
• She has a tiny waist.

Blessed vs Blest:

Someone help me out here. Can “Blessed” be used in place in “Blest” these days? I always thought this was the proper usage:
• Blessed are the meek – as in “Bless-UD”
• We are very blest

Peaked vs Peeked vs Piqued (added 1/5/10):

You might think that something peaks your interest because the word “peak” refers to the high point.  However, the correct word is “pique.”  This is a French word that translates to stimulate or anger. Here are the proper uses of these words:

• The lecture piqued my interest.
• The mountain peak was in sight.
• The dog peeked around the corner.
• The dog peeked at the mountain peak and his curiosity was piqued!

You and I vs You and Me (added 6/13/11):

I’ve been asked about this one several times so I decided to go back and add it to the list.   The easy way to fgure this one out is to remove the “You and” part and see if “I” or “me” makes sense.  For example:

• It’s up to you and ME to decide.  In this case, remove the part about you and say “It’s up to ME to decide.”  “It’s up to I to decide” makes no sense.
• You and I should go to Starbucks. Again, remove the part about you and test this phrase by saying “I should go to Starbucks.”  Only a caveman would say “Me should go to Starbucks.”

Seen vs Saw (added 6/13/11):

No one has asked about this, but I have heard it incorrectly used several times recently.  Only use “seen” when there is a “have” preceding it.

• I seen a green car today. WRONG WRONG WRONG
• I saw a green car today.  RIGHT RIGHT RIGHT
• I have saw a green car today.  WRONG WRONG WRONG
• I have seen a green car today.  RIGHT RIGHT RIGHT
• You can also replace “I have” with “I’ve” and still be correct.  “I’ve seen a green car today.”