Easily legible / recognizable from distance.
Bold print and/or bold identifiable element.
Incorporate cute cat or cat motif (cat, ears, tail, whiskers etc).
Playful and/or happy / positive aspect (just as examples - play on cat rubbing against legs - but not including legs, or cat head appearing from behind mischievously).
Simple / clean / crisp.
To be used on website, packaging (6"x9" bubble envelope), labels, stationery.
Also would be great to have a usable icon form of logo for use in twitter, etc).
Possible, but not necessary element: postage stamp (ex. perforated edges). As an example: http://cedarcomm.com/~stevelm1/Cind…Labels.htm