[June 08, 2010 Update]
I have updated my own site to use a theme called Scruffy. This theme has been updated to take full advantage of the new Blog Engine 1.6 feature set. To download the theme head on over to John Rummell's site here.
[Feb 24 2010 Update]
I just wanted to update this post to help keep it fresh. If you head over to CodePlex there is a download pack containing every existing theme for BlogEngine...well that's what they say but I know of a few that it's missing. Still, it's handy to have over 90% of the themes in the one download. I have also cleaned up the list below as some of the links were dead. If anyone has any new sites with more than 1 theme on them please let me know and I will update the list below.
[Original Post]
Since I started using BlogEngine.net I noticed that the one thing everyone complains about is that the themes are hard to find. I'd have to agree. There are theme sites out there but for some reason they're a little tricky to find.
Below is a list of the current BlogEngine theme sites I have found. These links aren't in any order. I'm also fairly confident that there are tons more sites out there with themes so feel free to add them to the comments and I'll update the list.
blogenginetheme.com - This is one of the larger theme collection sites out there for BlogEngine. The site promotes theme authors to upgrade their themes to be BE 1.5+ compatible by offering to place them on the first page of results if they do. This is a great idea to get some of the better BE 1.3/1.4 themes updated for use on the newer BlogEngine codebase.
onesoft.dk - some fantastic themes here and this is actually where I downloaded my first theme from. Unfortunately the site isn't updated as much as it was in the past but there are still some really nice themes to be found here. Mainly BE 1.3/1.4 themes here.
jankoatwarpspeed.com - This is one of my favourite website to visit. Janko is an ASP.NET guy like most of us (or at least I'm assuming you are because you use blogengine.net!) and regularly has great posts on .net and jquery that you might find interesting. As for themes he has a small collection (compared to the above list) but there are some nice themes here. You might find that you click through for the themes but stay for the content!
mooglegiant.net - There is a small collection of themes on this site. The themes are fairly basic in structure but sometimes that can be exactly what you need. I'm adding here because these themes can be easy and quick to modify and adjust. When you just want to knock out a blog for a client and need just a simple theme, one of these could hit the spot.
rtur.net - A small selection of themes (by which I mean 2) on this site but the developer keeps them up to date for BE 1.5.
geekiest.net - This blogger has a few blogengine themes up on his site. Many of the themes use designs from open source design sites but the list is always growing.
Obviously there is of course the BlogEngine.net site itself which has a large collection of themes on it's theme page and over at the unofficial forum. Most of the themes on those links appear to be older themes for BE 1.3/1.4.
Finally, if you're looking to get stuck in and making your own theme you can read a quick how to over at Al Nyveldt's blog. The screencast is targeted at slightly older versions of BE but the process is pretty much the same for 1.5. He is one of the main developers of BlogEngine and his site has tons of tips and tricks to get the most out of BlogEngine.
If you have any suggestions for some great theme sites out there for BlogEngine let me know and I'll be sure to include them on the list.