Distances and sizes are to scale, one pixel is 400km, making it by far the largest and most complete web-based scale model I've been able to find. Brightness (albedo) is not to scale, otherwise Mercury, Earth's Moon and the satellites of Jupiter would be far too dark to see clearly. This page is absolutely huge and may even crash some browsers. Internet Explorer has problems at Uranus and beyond, but doesn't crash, but I had to remove 90377 Sedna completely to make Firefox even display the page. At 96dpi, this page is 6.7km (4.2 miles) long out to Eris.
Radii are equatorial (or, for irregular and highly oblate objects, the mean diameter), distances are semimajor axis. When complete, all known objects larger than 400km (one pixel, adding the Kuiper Belt at the moment, bear with me there are a lot of 400km objects there) are presented and where possible actual imagery is used.
Planets
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
Dwarf Planets
1 Ceres 134340 Pluto 136472 Makemake 136199 Eris 136108 Haumea
Asteroids
2 Pallas 4 Vesta 10 Hygiea
Trans-Neptunian Objects
90482 Orcus 50000 Quaoar 28978 Ixion 20000 Varuna (84522) 2002 TC302 (55565) 2002 AW197 (19308) 1996 TO66 (24835) 1995 SM55 (120178) 2003 OP32 (145453) 2005 RR43 (55637) 2002 UX25 (225088) 2007 OR10
Moon
Jupiter Scroll right for satellites
Io
Europa
Ganymede
Callisto
Saturn Scroll right for satellites
Titan
Rhea
Iapetus
Dione
Tethys
Mimas
Enceladus
Titania
Oberon
Miranda
Ariel
Umbriel
Triton
Proteus
Charon