Western Digital My Book AV DVR Expander 1 TB USB 2.0/eSATA External Hard Drive for $99.99 + free shipping
1 TB external hard drive compatible with Tivo Premiere and Series 3 DVRs, among others. Easy way to upgrade the storage on your Tivo (you just plug the cable into the back). Price isn't spectacular, especially for a 1 TB harddrive, but Tivo is finicky about what hard drives it recognizes. I had been looking for these for a while, and hadn't had much luck finding them, as they had been sold out.
DVRs: Direct TV R15, HR20, HR2, HR23; Dish VIP722K; TiVo Series 3 & Premiere; Pace DC7581; Time Warner SA STB; Scientific Atlanta 8300
Camcorders: 2010 or later Sony camcorders with Direct Copy; WD My Book AV Box
Blu-ray Players: Sony 2010 Blu-ray Disc Players, Sony Blu-ray Disc Home Theater Systems, Samsung BD-P1600
Game Consoles (media playback only): Xbox 360, PS3
TVs: JVC LT-32P6, Samsung LN32A550, Phillips 42PFLA332D, LG 47LH30, Sony KDL-46XBR9
Media Players: Western Digital WD TV Live Plus, WD TV Live, WD TV, WD TV Mini