Bill, this may be more info than you want.... but around the shop I use several different methods to sharpen items.
Items such as mower blades, machete's, axe's, etc, typically get clamped in a vice, and rough sharpened with a hand held angle grinder (I use 7" Makita for rough sharpening [such as this one:
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200305673_200305673
For "maintnenance" sharpenings, I use a 4-1/2" version of the Makita to sharpen "on-mower". This sure beats the heck out of removing the blades!
Blades that are rough sharpened in the vise typically get a final sharpening using a 6" belt / 9" disc sander (slow speed Grizzly G1276) that is dedicated for metal working. Here is the model that I have:
The belt / disc sander is also used to sharpen chisels, drill bits (that are larger than my Darex sharpener will handle), carbide cutters, etc.
Precision tools such as drill bits, chisels, milling cutters, etc, receiving a final deburring with hand-held stones, like these:
http://www.jlindustrial.com/ADZ-06032E/SEARCH:KEYWORD/product.html
Less precise items such as axe's, etc, will receive a deburring with a hand held file.
An 8" bench grinder with a rough wheel on one side and a wire brush on the other is also in use - but rarely for sharpening (unless the item won't fit on the belt sander). The wire brush gets used ten times more than the grinding wheel, because I find that other methods outlined above are faster, more accurate, and offer better safety than the bench grinder. I use the wire brush for removing rust, scale, gunk, etc from bolt threads.
A 6" slow speed bench grinder with special wheels is dedicated for grinding tungsten tips for a TIG welder.
The WEK wet grinding machine in my tool cabinet has not been used in close to ten years...
My advice? - buy a hand held angle grinder (such as the Milwaukee model / Northern Tools pn 110312-1806 or 153396-0806), AND a slow speed belt / disc sander such as Grizzly model G1276 (
http://www.grizzly.com/products/Combination-Sander-6-x-48-Belt-12-Disc-1725-RPM/G1276). You can use the belt/disc sander for double "wood - metal" duty if you clean the belts after using it for metal and before using it for wood. This will help keep any small metal particals from becoming embedded in your wood projects. Another option is to simply change belts / discs for metal versus wood work.
The 4" grinder has the nice ability to do "double duty" as a woodworking rough carving grinder if you add a Lancelot fine carving tool to it. (
http://www.grizzly.com/products/Lancelot-Fine-Carving-Tool-22-Tooth-5-8-Arbor/G6692)
If you're on a tight budget, consider the Grizzly 4" grinder instead of the Milwaukee (
http://www.grizzly.com/products/Angle-Grinder-4-/G5968)
Hope this helps!
Scott