I applied the U-Coat It epoxy floor covering with my dad in his garage about 7 years ago and it still looks great despite seeing -10* temps + salt + sand in the winter and 100+* temps in the summer. IIRC it was around $500-$700 for a 500 square foot garage floor kit and included the cleaning materials, the etching solution, rollers and roller covers, primer, epoxy paint, colored chips, and a clear coat. Definitely worth it IMO.
Also, depending on where you live insulating a garage can be an excellent way to save gas and energy in the winter. With an attached garage you can easily see a 20+ degree increase from the cold temps outside if you have an insulated garage meaning your car will warm up faster and not waste as much gas trying to warm up.
At my last house, I had a detached single car garage... I insulated, sheetrocked, and painted it for under $500 and when it was 5* outside in the morning it would still be around 30-35* in the garage. Anyways, like wythors and revhead said the best thing you can do is to declutter by moving the gardening/yard stuff into a backyard shed.
In my new house we have a large 2 stall attached garage and my plan is to build an upper level in the garage w/ a 9' ceiling at the garage level. Ultimately I'll be insulating and sheetrocking everywhere, and will install an attic ladder to provide access to the upperlevel in the garage. This will allow me to have storage space for christmas decorations, and other junk that we don't use often but for some reason continue to keep.
I turn 30 next weekend and my wife already told me she's buying me the race deck equivalent from Sams Club for my birthday! I can't wait... gonna do black/white checkered floor I think... here's a link... it's about $1-$2 per square foot less than race deck.
http://www.samsclub.com/sams/shop/product.jsp?productId=prod4660075