Without much effort, you could do: 

A follow forever 

Promote or recommend a roleplay/roleplayer 

Say thank you x10000000

If you make graphics/use PS or a similar program, you could (depending on your expertise): 

Manips

Crackships 

Make icons of a faceclaim of choice 

Offer a theme makeover for any blog of choice 

Offer graphics for any blog of choice 

Make gifs for faceclaim of choice 

Make tutorial for something related to graphics you make 

Make PNGs for a faceclaim of choice

Create gradients/PSDs (if you have giveaway winners, you could name them after them). 

Create a bio graphic, (dedicated to a giveaway winner, follower, or friend).

Make a texture pack

Here are some non-graphic related ideas: 

Playlist based on a theme or idea given by winner 

Make a guide 

Make a masterlist 

Take gif hunt requests for faceclaim of choice 

Make a FC pack 

Take requests and write plots off of whatever inspiration you get

Make a font pack 

Make a photo hunt 

And some other out of the box ideas (for those with great skill):