Lemondrop

There are "Mail Goggles" to prevent regrettable e-mails and mandatory waiting periods for most weapons. So why hasn't someone come up with device to prevent something far more dangerous -- impulsive fashion choices?

Here's the next best thing: Sites that let you test drive new 'dos and avoid don'ts for everything from makeup to home decor. While they can't physically stop you, they may give you intellectual pause before, say, getting regrettably trendy baby bangs or a really bad couch.

For Beauty: Highlights or lowlights? Just a trim, or a total weedwhack? Put your questions to the interactive oracle at Taaz.com. It's a beauty-focused site where you can upload a pic of yourself and play around with haircuts and makeup until you find what fits. Then, take your look to the next level with hundreds of accessory combos at Dailymakeover.com.

Click here for more ways to test-drive looks before you leap ...

For Fashion: Sites from trendy H&M to dependable Land's End have applications that let you check out whether you can pull off a certain piece based on your your body type. We love the U.K. site Knickerpicker, which shows how certain bra and underwear styles will look on your body (or an approximation thereof) without any stripping down.

For Furnishing: UGallery.com is a pretty sweet site on its own -- it's a source for amazing art by emerging talent at seriously decent prices. But how will you know if a piece really matches your couch makes the artistic statement you're aiming for by looking at it on the Interwebs? Enter their Virtual Wall feature. You get to hang it in your space by recreating your room down to the exact furniture and colors.

For Design: Google SketchUp might be your new favorite timesuck. It lets you create 3D models of basically anything you'd want to design, whether it's a new deck on which to enjoy a margarita or a sofa that lets you find the perfect angle to watch TV horizontally.

For Interior Decorating: iPhone users with a decorating fetish and $10 to spare should peep this cool app. Interior designer Mark Lewison designed a service that helps you figure out whether the chair you saw out at the flea market really works with your current decorating style. It consolidates measurements, patterns and colors into one space so you can make snap judgments about any new piece you want to add.

Have a favorite makeover site that we forgot? Tell us in comments.