1. CValley Filter It!
Probably the most versatile Adobe Illustrator plug-in on the market today. With 3D Transform tool, Lens Tool and Craft Tool you can make some amazing effects that are not possible with any other plug-in. During last few years Adobe has adopted some of these effects so they are already available in Adobe Illustrator but what makes Filter-It so valuable is ease of use and versatility.
2. Hot Door CAD Tools
Set of high profile CAD tools will turn Illustrator into mini AutoCAD. Features include project or dimension flat art in isometric view, precision editing with fillet, chamfer, trim and extend tools etc.
Price: 279 full; $149 upgrade
3. Artlandia Symmetry Works
Artlandia SymmetryWorks is a plug-in for making repeat patterns in Adobe Illustrator. Despite the high price, this is nice tool for everyone working in textile or interior design industry.
4. Andrew's Vector Plug-ins
Collection of 25 plug-ins features Zoom Lines, GX Lines, GX Lattice Connect, Starburst, Random Touch, Contour, Perspective Grid, Gradients, Spiral and dozen more useful plug-ins that will help you to create some wonderful effects.
5. Stephen Vincent's Curvius
Curvius' 7 filters operate on selected path to create new artwork. This is nice set of tools for rather small price.
6. Stephen Vincent's Kimbo
Using only Cut and Rectangle Cut Tool is worth the price in this filter. With other featured filters like Rosette and Mirror you can create very complex objects out of simple shapes like circles or rectangles.
8. Esko Artwork Studio
Esko Artwork Studio is a plug-in for Adobe Illustrator that puts interactive 3D packaging creation in the hands of the designer. This plug-in is packed with features and is a great solution for anyone working with packaging design, although the pricing of this product is questionable at best.
Price: EUR 1200 (exl. VAT)
9. CoCut - Vinyl
Vinyl cutting solution for Adobe Illustrator, Corel Draw and AutoCAD. Supports all common cutting plotters.
Price: EUR 299
10. Embroidery i2
High-end embroidery design plug-in for Adobe Illustrator. It requires high speed internet connection to convert vectors to stitches. You cannot buy electronic version of this plug-in on the company's site, instead it's being sold through yearly subscription for $1600/year.